Expression of multiple isoforms of the cAMP-dependent protein kinase (PK-A) catalytic subunit in the nematode, Caenorhabditis elegans.
The cAMP-dependent protein kinase (protein kinase A, PK-A) plays a central role in the regulation of many aspects of eukaryotic cellular activity. In the free-living nematode, Caenorhabditis elegans, two genes encode PK-A-like catalytic subunits. The kin-1 gene has the potential to generate, through alternative splicing events, a multiplicity of catalytic subunit isoforms; in contrast, the F47F2.1b gene appears to encode just a single authentic catalytic subunit-like protein. Here, we report on the occurrence of, and developmental changes in the expression of, polypeptide products of these genes in both C. elegans and the closely related nematode, C. briggsae. Polypeptides derived from the F47F2.1 gene and its orthologue were detected in mixed stage populations of C. elegans and C. briggsae, respectively. Likewise, a number of polypeptides arising as a result of alternative splicing of transcripts from kin-1, or its orthologue in C. briggsae, were identified in mixed stage populations of nematodes. These isoforms included polypeptides with N-termini encoded by exons N'1 or N'4 and C-termini encoded by exons 7 or N. The expression of isoforms with an N-terminus encoded by the N'1 exon is of significance because the amino acid sequence encoded by this exon encompasses an N-myristoylation motif. Isoform abundance appears to be related to developmental stage. Substantial differences in polypeptide expression profiles can be seen in embryonic and adult nematodes. The functional significance of this PK-A catalytic subunit isoform diversity is discussed.
Bowen
Laura C
LC
Cellular Regulation and Signalling Group, School of Biological Sciences, University of Liverpool, L69 7ZB, UK.
Bicknell
Annalise V
AV
Tabish
Mohammad
M
Clegg
Roger A
RA
Rees
Huw H
HH
Fisher
Michael J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics; D019295:Computational Biology / Q000379:methods; D017868:Cyclic AMP-Dependent Protein Kinases / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D007527:Isoenzymes / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013997:Time Factors
D029742:Caenorhabditis elegans Proteins; D007527:Isoenzymes; D017868:Cyclic AMP-Dependent Protein Kinases