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FB2026_01
,
released March 12, 2026
Sema-2b, semaphorin
secreted - Ig superfamily - axon guidance - expressed by muscle 33 - functions by inhibiting the neuronal growth cone from forming a synaptic arborization (branching) to alternative muscles - epidermis-derived Semaphorin promotes dendrite self-avoidance by regulating dendrite-substrate adhesion in Drosophila sensory neurons
Please see the JBrowse view of Dmel\Sema2b 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 5.44
Stop-codon suppression (UGA) postulated; FBrf0216884
Gene model reviewed during 5.50
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Sema2b 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).
Sema2b is detectable in the ventral nerve cord No signal is detected in muscles, but expression can be found in a small number of peripheral cells whose positions were consistent with being sensory neurons.
JBrowse - Visual display of RNA-Seq signals
View Dmel\Sema2b in JBrowse2-80
2-82.4
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.
Sema-2b is required for ventromedial trajectory choice.
Axon-trajectory phenotypes of Sema-2b mutants have class-specific consequences for final target selection. For dorsolateral ORN classes, glomerular targeting is normal since Sema-2b is not required for their trajectory choice. For dorsomedial classes, initial axon trajectory choice is incorrect, but glomerular targeting is minimally affected, because target glomeruli are close to the midline commissure region where axons from ventromedial and dorsolateral trajectories reconvene. For ventromedial ORNs, incorrect trajectory choice has devastating consequences for targeting; axons that abberantly choose dorsolateral trajectories cannot take alternate routes to their targets but instead terminate in the dorsolateral antennal lobe far away from their normal targets.
Sema-2b can act cell-autonomously to instruct ventromedial axon trajectory choice.
Sema-2a and Sema-2b are both ligands of the plexB receptor, but they have different guidance functions during neurogenesis. Sema-2b functions at short-range as a guidance cue to promote axonal attraction, mediating axon-axon recognition and fasciculation, whereas Sema-2a acts over a broader range as a repulsive cue, to prevent aberrant innervation.
New annotation (CG30322) in release 3 of the genome annotation.
Identification: Defined on basis of sequence similarity to Sema-2a.
Source for merge of: CG30322 CG4383
Source for merge of: Sema-2b CG33960
Annotations CG30322 and CG4383 merged as CG33960 in release 4.3 of the genome annotation.
Source for identity of: Sema2b Sema-2b
