EVIDENCE FOR A 2ND ISOFORM OF THE CATALYTIC SUBUNIT OF CAMP-DEPENDENT PROTEIN-KINASE

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  • 25 November 1986
    • journal article
    • research article
    • Vol. 261  (33) , 5360-5363
Abstract
We have used a previously characterized mouse cDNA clone for the catalytic (C) subunit of cAMP-dependent protein kinase (Uhler, M. D., Carmichael, D. F., Lee, D. C., Chrivia, J. C., Krebs, E. G., and McKnight, G. S. (1986) Proc. Natl. Acad. Sci., U.S.A. 83, 1300-1304), which we designate C.alpha., to isolate cDNA clones coding for a second isoform of the C subunit, C.beta.. C.alpha. cDNA clones hybridize to a 2.4-kilobase mRNA on Northern blots whereas C.beta. cDNA clones detect a 4.3-kilobase mRNA. Nucleotide sequence comparison between C.alpha. and C.beta. cDNA clones shows that the c.beta. cDNA codes for a protein which shows 91% identity with C.alpha.. Determination of mRNA levels for C.beta. in various tissues shows that it is most highly expressed in brain although it is detectable in all tissues examined. The presence of two genes coding for the C subunit of cAMP-dependent protein kinase may explain past reports of heterogeneity in C subunit protein preparations.