Worm Breeder's Gazette 10(3): 63

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.

Characterization of G-proteins in C. elegans

Loesje van der Voorn, Hidde L. Ploegh and Ronald H.A. Plasterk

Figure 1

Guanine nucleotide-binding regulatory proteins (G-proteins) are a 
family of proteins involved in receptor-mediated signal transduction.  
G-proteins are heterotrimers, composed of alpha-,  - and gamma- 
subunits.  The alpha- subunit, which binds GTP, is specific for each G-
protein, whereas common  - and gamma- subunits may be found in some G-
proteins.  Subspecies of the alpha- subunit can be distinguished by 
their characteristic susceptibility to ADP-ribosylation catalyzed by 
cholera toxin and/or pertussis toxin.  We carried out ADP-ribosylation 
on a crude membrane fraction prepared from C.  elegans and found a 
polypeptide of 40 kD specifically labelled.  Moreover, antisera raised 
in rabbits against purified G-proteins from human and bovine brain, 
when used in Western blots on extracts from C.  elegans, likewise 
recognized a polypeptide of appr. 40 kD.  Combined, these findings 
argue for the existence of conserved C.  elegans G-protein alpha-
subunit(s) with remarkable similarity to their bovine and human 
In addition to the alpha-related polypeptides, the same antisera 
revealed the presence of a C.  elegans-polypeptide with a mobility 
identical to that of authentic human or bovine  -subunit.
By screening a C.  elegans library with a bovine  -probe, 12 
independent hybridizing clones were isolated.  Partial sequencing of 
one of these clones indicated the presence of a gene highly homogogous 
to  -sequences already known.  Over a stretch of 64 amino acids, 83% 
similarity with the bovine and human  -sequences is found (see box), 
confirming the identity of the C.  elegans  -subunit gene.
Further characterization of the  -clones and isolation of clones 
encoding the C.  elegans alpha-subunits is underway.
[See Figure 1]

Figure 1