Worm Breeder's Gazette 11(3): 33
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The unc-5 gene encodes a hypothetical trans-membrane receptor with an extracellular N-terminus, comprising one Ig and two tandem WSX domains, that could bind to unc-6 laminin B2, plus a large cytoplasmic C-terminus of unknown function (CSH Abstracts pp. 275, 276 (1989)). The cytoplasmic region contains a 50 aa sequence that is distantly related to the SH3 motif found in a variety of intracellular proteins associated with the membrane cytoskeleton including non-receptor tyrosine kinases (c-src, c-abl), phospholipase C (PLC), spectrin, type I myosins, and a yeast actin-binding protein (ABP1). All of these proteins interact, directly or indirectly, with actin microfilaments near the cell membrane. The function of the SH3 motif itself, however, is unknown for these proteins. unc-5 matches the SH3 consensus more poorly than bona fide SH3 proteins and may not be functionally related. However, unc-5 is required for guiding cell and axon migrations and local modulation of membrane cytoskeleton at the leading edge of migrating cells or growth cones has been proposed as a steering mechanism. In Drosophila, an SH3 protein, c-abl, affects axon growth in some mutant backgrounds. [See Figure 1]