Journal article
The testis-specific Ca2 subunit of PKA is kinetically indistinguishable from the common Ca1 subunit of PKA

Publication Details
Vetter, M.; Zenn, H.; Méndez, E.; Boom, H.; Herberg, F.; Skalhegg, B.
Publication year:
BMC Biochemistry
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The two variants of the a-form of the catalytic (C) subunit of protein kinase A (PKA), designated Ca1 and Ca2, are encoded by the PRKACA gene. Whereas Ca1 is ubiquitous, Ca2 expression is restricted to the sperm cell. Ca1 and Ca2 are encoded with different N-terminal domains. In Ca1 but not Ca2 the N-terminal end introduces three sites for posttranslational modifications which include myristylation at Gly1, Asp-specific deamidation at Asn2 and autophosphorylation at Ser10. Previous reports have implicated specific biological features correlating with these modifications on Ca1. Since Ca2 is not modified in the same way as Ca1 we tested if they have distinct biochemical activities that may be reflected in different biological properties.We show that Ca2 interacts with the two major forms of the regulatory subunit (R) of PKA, RI and RII, to form cAMP-sensitive PKAI and PKAII holoenzymes both in vitro and in vivo as is also the case with Ca1. Moreover, using Surface Plasmon Resonance (SPR), we show that the interaction patterns of the physiological inhibitors RI, RII and PKI were comparable for Ca2 and Ca1. This is also the case for their potency to inhibit catalytic activities of Ca2 and Ca1.We conclude that the regulatory complexes formed with either Ca1 or Ca2, respectively, are indistinguishable.


Last updated on 2019-25-07 at 11:18