hunchback, Rg-pbx
transcription factor - zinc finger - a gap gene later expressed in neuroblasts - required for proper temporal generation of cellular sublineages during neurogenesis
Please see the JBrowse view of Dmel\hb for information on other features
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AlphaFold produces a per-residue confidence score (pLDDT) between 0 and 100. Some regions with low pLDDT may be unstructured in isolation.
Gene model reviewed during 5.48
3.2, 2.9 (sequence analysis)
3.5, 3.2, 3.0, 2.8, 2.6 (northern blot)
3.2, 2.9 (northern blot)
758 (aa); 83 (kD predicted)
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\hb using the Feature Mapper tool.
The testis specificity index was calculated from modENCODE tissue expression data by Vedelek et al., 2018 to indicate the degree of testis enrichment compared to other tissues. Scores range from -2.52 (underrepresented) to 5.2 (very high testis bias).
Comment: maternally deposited
Comment: anlage in statu nascendi
Comment: anlage in statu nascendi
Comment: anlage in statu nascendi
Comment: reported as procephalic ectoderm anlage in statu nascendi
Comment: reported as procephalic ectoderm anlage in statu nascendi
Comment: reported as procephalic ectoderm anlage in statu nascendi
Comment: reported as procephalic ectoderm anlage
Comment: reported as procephalic ectoderm anlage
Comment: reported as procephalic ectoderm anlage
Comment: reported as procephalic ectoderm anlage
Comment: reported as procephalic ectoderm primordium
Comment: reported as procephalic ectoderm primordium
Comment: reported as procephalic ectoderm primordium
Comment: reported as procephalic ectoderm primordium
Comment: reported as procephalic ectoderm primordium
Comment: reported as procephalic ectoderm primordium
Comment: reference states 0-8 hr AEL
Comment: reference states 2-6 hr AEL
hb RNA and protein levels are time course were compared for the formation of the parasegment 4 stripe. The stripe is formed very quickly at the RNA level and is delayed and takes 5 times longer at the protein level. hb RNA and protein accumulation do not follow the same time course in the anterior and posterior domains.
hb transcripts are produced only by the germline-derived nurse cells. Transcripts are first detected at stage 7, increase dramatically in stages 8 and 9 and are no longer detectable by stage 12.
The hb transcript is expressed in the early embryo in two domains, an anterior domain which spans from the anterior tip to %50 egg length and posterior domain which spans from 90% egg length to the posterior tip.
The hb transcript is expressed in two broad regions in the cellular blastoderm, one which covers up to 50% egg length from the anterior and one which covers up to 20% egg length from the posterior.
The 3.0kb and 3.2kb hb transcripts accumulate to their highest levels over the first 8 hours of embryogenesis. They are also present in adult females and males with higher levels in females. In situ hybridization shows that the hb gene is first expressed uniformly over the embryo. In syncytial blastoderm embryos, expression is seen in a broad anterior stripe (50-100% EL) and a narrower posterior signal (0-15% EL). In late stage 4 embryos the anterior hb stripe weakens and narrows to two broad stripes. These are gone by the extended germ band stage when ventral hypoderm expression is seen.
The 2.8kb and 2.6kb hb transcripts are expressed only during first 6 hours of embryogenesis with a peak at 2-4 hrs. In situ hybridization shows that the hb gene is first expressed uniformly over the embryo. In syncytial blastoderm embryos, expression is seen in a broad anterior stripe (50-100% EL) and a narrower posterior signal (0-15% EL). In late stage 4 embryos the anterior hb stripe weakens and narrows to two broad stripes. These are gone by the extended germ band stage when ventral hypoderm expression is seen.
2.9kb hb transcripts are first detected at nuclear cycle 11-12 in the anterior half of the embryos and in the yolk nuclei in that region. Transcripts disappear at the beginning of gastrulation.
The 3.2kb hb transcripts are homogenously distributed in early embryos, then form an anterior-posterior gradient and are gone before the blastoderm stage. They appear again at nuclear cycle 13-14, where they form an anterior stripe at ~53% egg length and a posterior stripe. They are also expressed in the anterior yolk nuclei. The anterior stripe is in the region of the 2nd thoracic segment on the fate map and the posterior stripe is in the region of abdominal segments 7 and 8. The 3.2kb transcript persists throughout germ band extension.
The 2.9kb hb transcript is detected between 2 and 6 hours of embryonic development.
The 3.2kb hb transcript is present in maternal RNA and continues to be present for the first 8 hours of embryonic development. It is also detected in adult females.
hb RNA and protein levels are time course were compared for the formation of the parasegment 4 stripe. The stripe is formed very quickly at the RNA level and is delayed and takes 5 times longer at the protein level. hb RNA and protein accumulation do not follow the same time course in the anterior and posterior domains.
At embryonic stage 16 both hb-protein is detected in early-born neurons in the deepest layers of the embryonic CNS.
hb protein is detected in neurons of the male pupal brain and in the ventral nerve cord. A subset of neurons that express hb protein also express fru protein, and a subset of the latter are labelled by ScerGAL4fru-NP0021.
Expression assayed at stages 9, 11, 13, and 17. Expression may be continuous between assayed stages in some tissues.
Markers that uniquely identify the cells of the NB3-7 lineage were used to examine the serotonin expressing cell lineages.
Expression in procephalic neuroblasts stage 9-11: tritocerebrum - d3-7, v2; deuterocerebrum - d1, d13, v3, v4,v6; protocerebrum - ad1, ad3, ad4, ad14-15, ad17, av1, cd2, cd6, cd 7, cd13, cd18, cd19, cd21, cv1, cv3, cv6-9, pd3, pd15, pv2
JBrowse - Visual display of RNA-Seq signals
View Dmel\hb in JBrowse




3-45.4
3-48.3
Please Note FlyBase no longer curates genomic clone accessions so this list may not be complete
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see JBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
polyclonal
DNA-protein interactions: genome-wide binding profile assayed for hb protein in 2-3 hr embryos; see BDTNP1_TFBS_hb collection report.
hb is required for the specification of early sublineage of neuroblast 7-3.
The poly(A) tail is not required for regulation of hb maternal translation.
Individual phases of hb transcription, which overlap temporally and spatially, contribute specific patterning functions in early embryogenesis.
Persistence of hb protein in the terminal region of the blastoderm embryo impairs anterior development.
The embryonic CNS contains sequentially generated neuroblast sublineages that can be distinguished by their expression of either hb, nub or cas. hb and cas may directly silence nub expression in early and late developing sublineages, given that nub cis-regulatory DNA contains approximately 32 hb/cas-binding sites and its enhancer(s) are ectopically activated in cas- neuroblasts. Targeted misexpression of cas in all neuronal lineages reduces nub expression without altering hb expression. By ensuring correct POU gene expression boundaries hb and cas maintain temporal subdivisions in the cell-identity circuitry controlling CNS development.
Mutants are isolated in an EMS mutagenesis screen to identify zygotic mutations affecting germ cell migration at discrete points during embryogenesis: mutants exhibit gap pattern defects.
Quantifying rates of protein sequence divergence within and between species reveals that the Drosophila genome harbors a substantial proportion of genes with a very high divergence rate.
Gene product is known to regulate Kr CD (cis acting control element) expression.
A 1.4kb region of hb upstream sequence has been identified and characterised and found to be both necessary and sufficient for the normal expression and function of the gene in the posterior blastoderm stage embryo.
The products of the Taf4 and Taf6 loci serve as coactivators to mediate transcriptional activation by the bcd and hb enhancer binding proteins. A quadruple complex containing Tbp, Taf1, Taf4 and Taf6 mediates transcriptional synergism by bcd and hb, whereas triple Tbp-Taf complexes lacking one or other coactivator failed to support synergistic activation. The concerted action of multiple regulators with different coactivators helps to establish the pattern and level of segmentation gene transcription during development.
The first and second finger domains of hb are separable and the region between the domains (the D box) is specifically involved in the regulation of a subset of genes.
Enhancer elements of hb and Dvir\hb include highly conserved sequence blocks. The regulatory and coding regions of Dvir\hb are fully functional in D.melanogaster and are regulated very much like the endogenous hb gene.
Comparisons of early development to that in other insects have revealed conservation of some aspects of development, as well as differences that may explain variations in early patterning events.
hb is autonomously capable of activating the target gene Kr at low concentrations and repressing it at high concentrations. An artificially created hb gradient can organize a large part of the segment pattern, although it is expressed at a different position and in a different shape than the wild type pattern of hb.
Ectopic ttk expression has no effect on expression of Kr and hb.
Expression of hb has been used as a marker for a subset of neuroblasts in study of requirement for wg gene product for neuroblast specification and formation in the CNS.
Expression of prd depends on activation by gap gene hb, Kr, kni and gt products. Primary pair rule gene products act primarily in subsequent modulation rather than activation of prd stripes. Factors activating prd expression in the pair rule mode interact with those activating it along the dorso-ventral axis.
Translation of hb affected similarly by pumilio product and nos product.
Embryos with nanos artificially localised anteriorly show suppressed maternal hb expression, leading to the production of a second abdomen, acting through the gap genes.
hb binding sites in Ubx promoter region function to suppress ectopic ftz-mediated activation outside Ubx expression domain.
In csw- embryos hb remains as a posterior cap and the seventh ftz stripe expands posteriorly, both due to lack of hkb repressing activity.
The gene products of bcd, hb, Kr and gt all bind within the 480bp region that is necessary and sufficient for the expression of eve stripe 2. Activation depends on cooperative interactions between hb and bcd.
Orthologs present in M.domestica, C.vicina, P.cinerea, A.mellifera, T.castaneum, E.plebejus, S.lampyridiformis, L.migratoria, P.phalangoides, L.forficatus, B.tentaculata and P.dumerilii.
Sequence alignments of orthologous fragments of hb, Kr and sna from a variety of arthropods and other phyla show that amino acid differences are not normally correlated with evolutionary distance between respective species. Amino acids directly involved in DNA binding are the most conserved, and binding specificity of a hb finger from different species is not changed.
hb controls thoracic and abdominal segmentation by acting as a classical gradient morphogen.
hb does not mediate the activating effect of bcd on gt anterior expression as shown by the slight anterior shift of stripe 3 in hb mutant embryos.
Expression from the Ecol\lacZ-Kr730 Kr-promoter fusion construct was monitored in hb- embryos to ensure the target site for hb mediated Kr expression had not been lost.
hb has a slight repressive effect on gt expression in the posterior of the embryo.
Mutations in zygotic cardinal gene hb do not interact with RpII140wimp.
Zygotically active locus involved in the terminal developmental program in the embryo.
The 145 bp region carrying the hb1 and hb2 nos response elements (NRE) is essential for cis-acting nos mediated hb repression. The sensitivity of maternal hb mRNA to regulation by nos depends on the number and quality of the NREs in the transcript: two copies confers greater sensitivity than one. The degree of regulation mediated by the NREs depends on the level of nos.
hb is a concentration-dependent activator of transcription.
hb mutants exhibit a deletion in the head and thorax.
Characterisation of the crude RNA polymerase II transcription system using transcription initiation of the hb promoter.
Mutations in hb alter gt expression in the posterior of the embryo.
Ecol\lacZ reporter gene has been used to define cis-acting regulatory sequences of hb. A 123bp core region is both necessary and sufficient for activation, this may depend on component elements, one of which can substitute the other when present in multiple copies. These elements respond only where the levels of bcd gene product exceed threshold levels. The elements can mediate bcd-dependent gene activation in a yeast heterologous system.
The evolutionary divergence of both the primary DNA sequence and the spatial expression pattern of Dvir\hb and D.melanogaster hb has been investigated.
Northern analysis demonstrates that hb encodes at least five overlapping transcripts divisible into two classes based on structure and time of expression.
hb gene activity is involved in the establishment of the Antp parasegment 4 domain.
Mutant embryos exhibit normal Dfd expression.
hb was involved in a complementation analysis of the 85A region.
Ecol\lacZ reporter gene constructs have been used to investigate the hb cis-regulatory region and therefore the regulation of the hb transcripts. The 3.2kb transcript is required for the correct formation of abdominal segments 7 and 8 and the second thoracic segment. Anterior activation of the 2.9kb transcript is essential for gap gene function of hb.
Involved in functions related to that of tll.
Developmental studies of hb mutants suggest that the hb gene product is required during early development at the onset of gastrulation.
hb behaves genetically as an antagonist of Pc, their mutant combinations lead to the ectopic expression of genes from the BXC and ANTC. Insufficiency of Pc products can be corrected by insufficiency of hb products or be exaggerated by the excess of the same products.
hb mutants display deletion of gnathal and thoracic segments.
Homozygotes for null alleles of hb (class I alleles of Lehmann and Nusslein-Volhard, 1987) are embryonic lethals of the gap type. Gastrulation abnormal; no cephalic fold; cell death evident at 6 hr later becoming extensive, predominantly in the neuroectoderm; germ band extension curtailed at 50% of embryonic length. After germ band shortening embryos lack thoracic and labial segments; cephalopharyngeal skeleton present but poorly formed; head involution fails. Seventh and eighth abdominal segments fused by the deletion of parasegment 13; A1 segment 1.5 times normal width, with eight to ten deranged denticle rows compared to the normal number of four, and a widened region of naked cuticle. Filzkorper material reduced; posterior spiracles fail to evert. Three ventral ganglia absent; gap appears between suboesophogeal region of ventral nerve cord and more posterior trunk ganglia. Extreme mutants display a reduced number of stripes of ftz expression at cellular blastoderm; the first stripe is widened and followed by a narrowed gap of nonexpression preceding the second stripe; the last pair of stripes are fused (Carroll and Scott, 1986). Hypomorphic alleles display variably less severe disruption depending on allele (hbDrv6 = hbb2 = hbe21 > hbb7 > hbDrv9), the least severe, hbDrv9 lacking only T2. Class II alleles (Lehmann and Nusslein-Volhard) resemble the null alleles except that some or all of the prothorax and A7 are retained. The class III allele retains the labial segment as well. Class IV alleles lack only the mesothoracic segment. Class V mutants exhibit segment transformations as well as gaps and are described separately in the allele records. Temperature sensitive period of hbts1 during first four hr of development. hb/+ offspring produced from homozygous oogenic clones develop normally; homozygous embryos resulting from such clones display enhanced zygotic phenotype; gnathal, thoracic and the first three abdominal segments replaced by two or three segments of abdominal identity in mirror image relation to the more posterior abdominal segments; weak alleles without maternal effect; extra doses of hb+ in female without effect on phenotype of hb offspring. The anterior zone of hb expression extended posteriorly by six additional cells in the absence of Kr+; conversely the zone of Kr expression expanded anteriorly by six to eight cells in hb mutants; posterior zone appears insensitive to Kr constitution (Jackle, Tautz, Schuh, Seifert and Lehmann, 1986). hb+ appears to set the boundaries of Ubx expression (White and Lehmann, 1986); zone of Ubx expression expanded in both anterior and posterior directions in hb mutant embryos at the stage of full germ band elongation; segmental disposition of expression characteristically deranged prior to the advent of cell death. Although Ubx expression in the ventral nerve chord at the stage of fully shortened germ band extends from parasegments 5-13, Ubx protein detected in parasegments 1, 7-12 and 14 in hb12, 3 and 7-14 in hb1 and head to parasegment 1 plus parasegments 7-12 and 14 in hb7 (White and Lehmann). Phenotypic effects of ftz and hb in double mutants additive in thorax and anterior abdomen, but more severe than expected in head and posterior regions.
Source for merge of: Rg-pbx hb
Source for identity of: hb CG9786
The original gene name "hunchback" (hb) was changed to "hb transcription factor" (hb) to eliminate its potentially offensive association with human conditions.