Abstract
Accurate calcium signaling requires spatial and temporal coordination of voltage-gated calcium channels (VGCCs) and a variety of signal transduction proteins. Accordingly, regulation of L-type VGCCs involves the assembly of complexes that include the channel subunits, protein kinase A (PKA), protein kinase A anchoring proteins (AKAPs), and beta2-adrenergic receptors, although the molecular details underlying these interactions remain enigmatic. We show here, by combining extracellular epitope splicing into the channel pore-forming subunit and immunoassays with whole cell and single channel electrophysiological recordings, that AKAP79 directly regulates cell surface expression of L-type calcium channels independently of PKA. This regulation involves a short polyproline sequence contained specifically within the II-III cytoplasmic loop of the channel. Thus we propose a novel mechanism whereby AKAP79 and L-type VGCCs function as components of a biosynthetic mechanism that favors membrane incorporation of organized molecular complexes in a manner that is independent of PKA phosphorylation events.
Highlights
Accurate calcium signaling requires spatial and temporal coordination of voltage-gated calcium channels (VGCCs) and a variety of signal transduction proteins
The AKAP79mediated enhancement of current amplitude did not require the presence of a calcium channel 1b subunit (Fig. 1, B and C; ϩ1b, IAKAP/I ϭ 3.1 Ϯ 0.2, n ϭ 26; Ϫ1b, IAKAP/I ϭ 2.9 Ϯ 0.5, n ϭ 8) and was not altered following coexpression of distinct forms of -subunits, indicating that the effect of AKAP79 is intrinsic to the L-type calcium channel ␣1 subunit
To test whether the protein kinase A (PKA)-AKAP interaction is a prerequisite for the AKAP79 effects, we injected the oocytes during the time course of the recordings with the AKAPlbcderived peptide Ht-31 (50 M final concentration) that contains the critical RII-binding domain and is known to prevent association of PKA with AKAPs [23]
Summary
Accurate calcium signaling requires spatial and temporal coordination of voltage-gated calcium channels (VGCCs) and a variety of signal transduction proteins. By combining extracellular epitope splicing into the channel pore-forming subunit and immunoassays with whole cell and single channel electrophysiological recordings, that AKAP79 directly regulates cell surface expression of L-type calcium channels independently of PKA.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
