title: Inactive forms of the catalytic subunit of protein kinase A are expressed in the brain of higher primates.
abstract: It is well documented that the beta-gene of the catalytic (C) subunit of protein kinase A encodes a number of splice variants. These splice variants are equipped with a variable N-terminal end encoded by alternative use of several exons located 5' to exon 2 in the human, bovine and mouse Cbeta gene. In the present study, we demonstrate the expression of six novel human Cbeta mRNAs that lack 99 bp due to loss of exon 4. The novel splice variants, designated CbetaDelta4, were identified in low amounts at the mRNA level in NTera2-N cells. We developed a method to detect CbetaDelta4 mRNAs in various cells and demonstrated that these variants were expressed in human and Rhesus monkey brain. Transient expression and characterization of the CbetaDelta4 variants demonstrated that they are catalytically inactive both in vitro against typical protein kinase A substrates such as kemptide and histone, and in vivo against the cAMP-responsive element binding protein. Furthermore, co-expression of CbetaDelta4 with the regulatory subunit (R) followed by kinase activity assay with increasing concentrations of cAMP and immunoprecipitation with extensive washes with cAMP (1 mm) and immunoblotting demonstrated that the CbetaDelta4 variants associate with both RI and RII in a cAMP-independent fashion. Expression of inactive C subunits which associate irreversibly with R may imply that CbetaDelta4 can modulate local cAMP effects in the brain by permanent association with R subunits even at saturating concentrations of cAMP.
authors: Department of Nutrition, Institute for Basic Medical Sciences, University of Oslo, Norway.
authors: Anja C V
authors: AC
authors: Larsen
authors: Anne-Katrine
authors: AK
authors: Kvissel
authors: Tilahun T
authors: TT
authors: Hafte
authors: Cecilia I A
authors: CI
authors: Avellan
authors: Sissel
authors: S
authors: Eikvar
authors: Terje
authors: T
authors: Rootwelt
authors: Sigurd
authors: S
authors: Ørstavik
authors: Bjørn S
authors: BS
authors: Skålhegg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology*; D020134:Catalytic Domain; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers; D006801:Humans; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D011323:Primates; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D017931:DNA Primers; D017868:Cyclic AMP-Dependent Protein Kinases