Worm Breeder's Gazette 13(1): 46 (October 1, 1993)

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.


Leslie Lobel, Bob Horvitz.[1], Manfred Grabner, Hartmut Glossmann[2]

[1]HHMI, Dept. Biology, MIT, Cambridge, MA 02139, USA
[2]Dept. Biochemical Pharmacology, University of Innsbruck, Austria..

We recently reported (1993 C. elegans meeting) the cloning of unc-36 ,a gene that encodes a protein similar to the a lpha2 subunit of the voltage-gated calcium channel from mammals. Since then we isolated DNA clones by PCR encoding homologous sequences to portions of the a lpha1 and beta subunits of the calcium channel. The a lpha1 clone is 1 kb in length and has 52% identity and 74% similarity to a rodent a lpha1 subunit. The beta clone is only 250 bp in size and has 68% identity and 76% similarity to a human beta clone. We have used these clones to probe the YAC polytene filters (provided by Alan Coulson). Our results indicate that there are at least two loci encoding an a lpha1 homologous peptide, and at least five loci encoding beta homologous peptides. Our results are summarized below.

There are at least two loci encoding a lpha1 subunits: a) LGIV near eat-12 / egl-19 .Positive YACs Y51C8 and Y49F12 .Positive cosmids C11E10 , K11C12 , B0496 ,and C48A7 .b) LGII between fer-15 and rol-6 .Positive YAC Y24H1 .

There are at least five loci encoding beta subunits: a) LGI near ces-2 .Positive YACs Y62C9 and Y65E10 .b) LGIV near let-280 , let-281 , let-282 , let284 .Positive YACs Y53H3 and Y38A7 .c) LGV near ric-4 .Positive YACs Y47H11 , Y22G9 and Y54B9 .Positive cosmid C14H1 .d) LGX near vit-3 , vit-4 .Positive YAC Y60B6 .e) LGX between unc-6 and dpy-7 .Positive YACs Y51D11 and Y53D9 .

The identification of multiple loci encoding a lpha1 and beta homologous peptides agrees well with the variety of voltage-gated calcium channels being isolated from mammals. It has been demonstrated, for example by Campbell's laboratory (ref. 1 and personal communication), that the physiological classification of voltage-gated calcium channels (i.e. L and N) corresponds to slight antigenic variation between the subunits of these channel types. Our identification of multiple a lpha1 and beta subunit loci may be a manifestation of the variety of voltage-gated channels in C. elegans.

We plan to screen a cDNA library with these clones and use the cDNAs to produce subunit specific antibodies. We are also testing previously isolated mutants that map near the above loci for defects in these calcium channel subunits.

l) Witcher D., De-Waard M., Sakamoto J., Franzini-Armstrong C., Pragnell M., Kahl S.D., Campbell K.P. Science, 261, 486,1993.