Worm Breeder's Gazette 10(3): 44

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.

lin-12 and glp-1 Encode Very Similar Potential Transmembrane Proteins

John Yochem and Iva Greenwald

Figure 1

The lin-12 and glp-1 genes have each been implicated in certain cell-
cell interactions during C.  elegans development (Greenwald et al., 
1983; Austin and Kimble, 1987; Priess et al., 1987).  Evidence was 
presented in the previous issue of the Gazette that these genes are 
related at the sequence level (Yochem and Greenwald, p.  84; Austin 
and Kimble, p. 85; Fire and Priess, p. 86).  The complete DNA 
sequencing of genomic and cDNA clones of glp-1 has now been finished, 
permitting an overall comparison with the complete sequence of lin-12 (
Yochem et al., 1988).  Iin-12 and glp-1 appear to have evolved from a 
common ancestor, since several splice junctions are conserved and 
their products are strikingly similar (the overall identity is about 
50%), although the glp-1 product contains only ten copies of the EGF-
like motif found 13 times in lin-12, and is therefore smaller (1295 
versus 1429 amino acids).  The predicted primary products are aligned 
below in schernatic form relative to a strongly hydrophobic stretch of 
amino acids which could serve as a membrane spanning domain.  Both 
products contain a somewhat similar sequence ('T + Y-encoded sequence')
that does not completely resemble EGF after their first copy of the 
EGF-like motif, three copies of a cysteine-rich sequence ('LNR') that 
does not resemble EGF, and six copies of a motif (Breeden and Nasmyth, 
1987) in their cytoplasmic regions that is also present in two yeast 
gene products (Schizosaccharomyces pombe cdc10, Saccharomyces 
cerevisiae SWI6).  The lin-12 and glp-1 products also have an 
intriguing overall resemblance to the product predicted for the 
Drosophila Notch gene (Wharton et al., 1985; Kidd et al., 1986 ), 
which has also been implicated in cell-cell interaction during 
development.  The lin-12 and glp-l gene products are much more closely 
related to each other than to the Notch product, and the extent of 
divergence suggests that Notch is not a counterpart of either.  A more 
reasonable consideration is that these genes define a new family with 
individual members possessing related but distinct functions during 
[See Figure 1]

Figure 1