AKAP79 modulation of L-type channels involves disruption of intramolecular interactions in the CaV1.2 subunit.
L-type voltage gated calcium channels (VGCCs) interact with a variety of proteins that modulate both their function and localization. A-Kinase Anchoring Proteins (AKAPs) facilitate L-type calcium channel phosphorylation through β adrenergic stimulation. Our previous work indicated a role of neuronal AKAP79/150 in the membrane targeting of Ca(V)1.2 L-type calcium channels, which involved a proline rich domain (PRD) in the intracellular II-III loop of the channel.(1) Here, we show that mutation of proline 857 to alanine (P857A) into the PRD does not disrupt the AKAP79-induced increase in Ca(v)1.2 membrane expression. Furthermore, deletion of two other PRDs into the carboxy terminal domain of Ca(V)1.2 did not alter the targeting role of AKAP79. In contrast, the distal carboxy terminus region of the channel directly interacts with AKAP79. This protein-protein interaction competes with a direct association of the channel II-III linker on the carboxy terminal tail and modulates membrane targeting of Ca(V)1.2. Thus, our results suggest that the effects of AKAP79 occur through relief of an autoinhibitory mechanism mediated by intramolecular interactions of Ca(v)1.2 intracellular regions.
Department of Physiology and Pharmacology, University of Calgary, Alberta, Canada.
Christophe
C
Altier
Stefan J
SJ
Dubel
Christian
C
Barrere
Scott E
SE
Jarvis
Stephanie C
SC
Stotz
John D
JD
Scott
Joel
J
Nargeot
Gerald W
GW
Zamponi
Emmanuel
E
Bourinet
D054758:A Kinase Anchor Proteins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D020746:Calcium Channels, L-Type / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D017353:Gene Deletion; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009865:Oocytes; D018408:Patch-Clamp Techniques; D011392:Proline / Q000378:metabolism; D055232:Proline-Rich Protein Domains; D054730:Protein Interaction Domains and Motifs; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D014981:Xenopus
D054758:A Kinase Anchor Proteins; C487775:AKAP5 protein, human; C514350:CACNA1C protein, mouse; D020746:Calcium Channels, L-Type; D021122:Protein Subunits; D011392:Proline