Worm Breeder's Gazette 5(2): 18

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.

Peptide Mapping of Adult C. elegans Cuticle Proteins

J. Politz

SDS-PAGE of the SDS- ME soluble cuticle proteins of adult C.  
elegans reveals eight major bands ranging in apparent MW from 53K - 
212K.  We call these cpA, cpB, cpC, cpD, cpE, cpF, cpG, and cpH.  cpA 
is the lowest MW band, cpH the highest.  The results of a number of 
experiments indicate that these proteins are collagen-like.
In order to further characterize these proteins, I have compared 
them using the one-dimensional peptide mapping procedure of Cleveland 
et al.  (JBC 252, 1102 (1977)).  This method allows partial enzymatic 
digestion of proteins in excised SDS acrylamide gel bands and 
simultaneous electrophoretic separation of the cleavage products.
Peptide maps of each of the eight major bands using chymotrypsin, S. 
aureus V8 protease, and papain were compared and contrasted.  The 
results indicate definite homology between the proteins in the 
different bands.  Some proteins are more closely related than others, 
and on this basis, fall into three classes: cpA and cpC; cpB, cpD, cpF,
cpG and cpH; and cpE.  The peptide maps of cpF, cpG, and cpH are 
nearly identical.  The maps of the other five proteins each contain 
unique fragments.
One interpretation of these results is that the cuticle collagens 
are produced by a family of cuticle genes, distinct yet closely 
related.  Since collagens contain highly repetitive sequences, it may 
be expected that a certain degree of homology be present.  The extent 
of homology could vary depending on when during their evolution the 
genes diverged from one another.
The results of these experiments are equally compatible with a 
second interpretation.  Some of the proteins may be crosslinked 
aggregates of smaller proteins (monomers).  Many collagens are known 
to be covalently crosslinked during post-translational modification.  
Peptide maps of such crosslinked proteins would be similar but not 
identical to peptide maps of the monomers, e.g.  crosslinked 
polypeptides would appear as unique bands.
Further experimentation is necessary to distinguish between these 
two possibilities.  I am now beginning to isolate the mRNAs coding for 
these cuticle collagens; hopefully this will help clarify the 
situation.