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.

An SH3 Motif in the Cytoplasmic Domain of the unc-5 Protein?

E. Hedgecock, B. Stern, J. Culotti, C. Leung-Hagesteijn and A. Spence

Figure 1

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]

Figure 1