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FB2026_01
,
released March 12, 2026
DmHD-265, DROSEV1
transmembrane - receptor TK - required for the development of the R7 photoreceptor - Sevenless signaling from somatic cells is required to ensure that the niche develops in the anterior region of the male embryonic gonads
Please see the JBrowse view of Dmel\sev for information on other features
To submit a correction to a gene model please use the Contact FlyBase form
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 5.50
8.6 (northern blot)
There is only one protein coding transcript and one polypeptide associated with this gene
2554 (aa); 288 (kD predicted)
It is unclear whether the potential membrane spanning region near the N-terminus is present as a transmembrane domain in the native protein or serves as a cleaved signal sequence.
May form a complex with drk and Sos. Binds the phosphotyrosine interaction domain (PID) of Dab.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\sev 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: 6hrs APF
Comment: 12hrs APF
Comment: 24hrs APF
JBrowse - Visual display of RNA-Seq signals
View Dmel\sev in JBrowsePlease 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.
dsRNA made from templates generated with primers directed against this gene tested in RNAi screen for effects on Kc167 and S2R+ cell morphology.
Mutant eye phenotype suggests sev function is restricted to R7 photoreceptor determination.
Phylogenetic analysis of the PTK family.
The protein encoded by dos is a csw substrate and may also be a direct or indirect target for the tyrosine kinase activity of sev. Mutations that inactivate dos dominantly enhance the effects of reduced csw activity and suppress the effects of either excessive sev or csw activity. Results indicate that dos is a crucial component of the sev signalling pathway and strongly suggest that dephosphorylation of dos by csw promotes R7 photoreceptor differentiation.
pros gene becomes transcriptionally activated at a low level in all sev-competent cells prior to sev signaling and this requires the activities of Ras85D and two ETS transcription factors, aop and pnt. Restriction of high level pros expression to the R7 cell appears as a subsequent event, which requires sev activation of the Ras85D kinase pathway.
Variation of a microsatellite within the sev locus has been studied in North American populations of D.melanogaster.
In vitro studies show that boss activates tyrosine phosphorylation of the sev receptor and the transmembrane domain of boss is necessary for its function. A soluble form of boss acts as an antagonist of the sev receptor both in vivo and in vitro.
Functional interchangeability of D.melanogaster and D.virilis sev and boss were demonstrated using chimeric genes.
As part of a study of an R7-lacking strain of D.virilis, the surface of a sev mutant eye was examined by scanning electron microscopy: occasional irregularities where two surface hairs relace the usual one per ommatidium were described.
Antibody staining demonstrates that the entire boss protein is internalized by sev-expressing tissue culture cells and by the R7 precursor cell in the developing eye imaginal disc demonstrating the receptor mediated transfer of a transmembrane ligand.
Results obtained using a constitutively active sevenless kinase show that competence to develop as neuronal cells is spatially and temporally limited to sevenless-expressing cells, thereby revealing that the expression of sev marks a preexisting pattern of developmental potential. sev and sina act in a pathway required for neuronal development, rather than R7 cell fate per se.
The phl serine/threonine kinase plays a crucial role in the R7 pathway: the response to sev gene product activity is dependent on phl function, and a constitutively activated phl protein can induce R7 cell development in the absence of sev function. Genetic evidence suggests that phl acts downstream of Ras85D and upstream of sina in this signal transduction pathway.
Some aspect of R7 differentiation is independent of the genetic pathway involving sev, boss and sina as some P{HZ}klgH214 expression is present in R7 of sev mutants.
The R8 photoreceptor neuron induces a neighbouring cell to assume an R7 cell fate. The induction is mediated by two transmembrane proteins encoded by sev and boss.
A genetic screen for mutations that decrease the effectiveness of signalling by sev identified 7 genes, enhancers of sevenless, that when mutated make the phenotype of sevB4 more severe.
Mutant analysis of sev (unspecified) provides evidence for the participation of a G0-like protein in learning and memory. Sex-dependent enhancement in pertussis toxin catalysed ADP-ribosylation with respect to wild type: attributed in part to an increase in the α subunit of the G0-like protein.
The predicted amino acid sequences of D.melanogaster sev and Dvir\sev have been compared.
Mutant analysis demonstrates that sev defines a class of tyrosine kinases likely to be involved in cell-cell communication during development.
The sev gene, required for photoreceptor R7 development, encodes a putative cell surface receptor bearing a cytoplasmic tyrosine kinase domain.
Homozygotes and hemizygotes lack the R7 rhabdomere in all ommatidia; the R7 photoreceptor cell instead develops as an accessory lens-secreting cell, the equatorial cone cell (Tomlinson and Ready, 1986; Tomlinson and Ready, 1987). Cell autonomous in mosaics (Harris, Stark and Walker, 1976). Mosaic analysis demonstrates that sev+ product is required only in the presumptive photoreceptor 7 cell and is therefore involved in receiving signals from neighboring cells. Electroretinograms normal; defective in response to ultraviolet; in T-maze tests sev flies prefer visible to ultraviolet wavelengths and green light to darkness; slight preference for blue wavelengths over ultraviolet used in selecting mutant alleles (Gerresheim, 1988). In the presence of Ppb the preference of green light to darkness is reversed for sev1 and sev10 but not for six other unspecified alleles; the absence of R7 is unaffected by Ppb (Ballinger and Benzer, 1988). Gene expression demonstrated by in situ hybridization and immune staining to take place in developing eye imaginal disc, near and posterior to the morphogenetic furrow, during ommatidial differentiation. Protein present transiently in at least nine cells in each developing ommatidium and is detectable before any overt differentiation of R7 observed (Tomlinson, Bowtell, Hafen and Rubin, 1987; Banerjee, Renfranz, Hinton, Rabin and Benzer, 1987). Transient expression of sev+ by means of a transformed construct under control of the Hsp70 promoter in a sev background results in a narrow stripe of ommatidia that contain photoreceptor cell 7 in eyes that are otherwise sevenless; the position and time of expression required for normal function are highly restricted (Bowtell, Simon and Rubin, 1989).
Identified by PCR fragment; relationship to other protein tyrosine kinase genes not known.
Source for identity of: sev CG18085
