+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Anchoring protein AKAP79-mediated PKA phosphorylation of STIM1 determines selective activation of the ARC channel, a store-independent Orai channel

Anchoring protein AKAP79-mediated PKA phosphorylation of STIM1 determines selective activation of the ARC channel, a store-independent Orai channel

Journal of Physiology 593(3): 559-572

Although both the calcium store-dependent CRAC channels and the store-independent ARC channels are regulated by the protein STIM1, CRAC channels are regulated by STIM1 in the endoplasmic reticulum, whilst ARC channels are regulated by the STIM1 constitutively resident in the plasma membrane. We now demonstrate that activation of the ARC channels, but not CRAC channels, is uniquely dependent on phosphorylation of a single residue (T389) in the extensive cytosolic domain of STIM1 by protein kinase A. We further demonstrate that the phosphorylation of the T389 residue by protein kinase A is mediated by the association of plasma membrane STIM1 with the scaffolding protein AKAP79. Together, these findings indicate that the phosphorylation status of this single residue in STIM1 represents a key molecular determinant of the relative activities of these two co-existing Ca(2+) entry channels that are known to play critical, but distinct, roles in modulating a variety of physiologically relevant activities. The low-conductance, highly calcium-selective channels encoded by the Orai family of proteins represent a major pathway for the agonist-induced entry of calcium associated with the generation and modulation of the key intracellular calcium signals that initiate and control a wide variety of physiologically important processes in cells. There are two distinct members of this channel family that co-exist endogenously in many cell types: the store-operated Ca(2+) release-activated CRAC channels and the store-independent arachidonic acid-regulated ARC channels. Although the activities of both channels are regulated by the stromal-interacting molecule-1 (STIM1) protein, two distinct pools of this protein are responsible, with the major pool of STIM1 in the endoplasmic reticulum membrane regulating CRAC channel activity, whilst the minor pool of plasma membrane STIM1 regulates ARC channel activity. We now show that a critical feature in determining this selective activation of the two channels is the phosphorylation status of a single threonine residue (T389) within the extensive (∼450 residue) cytosolic domain of STIM1. Specifically, protein kinase A (PKA)-mediated phosphorylation of T389 of STIM1 is necessary for effective activation of the ARC channels, whilst phosphorylation of the same residue actually inhibits the ability of STIM1 to activate the CRAC channels. We further demonstrate that the PKA-mediated phosphorylation of T389 occurs at the plasma membrane via the involvement of the anchoring protein AKAP79, which is constitutively associated with the pool of STIM1 in the plasma membrane. The novel mechanism we have described provides a means for the cell to precisely regulate the relative activities of these two channels to independently modulate the resulting intracellular calcium signals in a physiologically relevant manner.

Please choose payment method:

(PDF emailed within 0-6 h: $19.90)

Accession: 057197314

Download citation: RISBibTeXText

PMID: 25504574

DOI: 10.1113/jphysiol.2014.284182

Related references

Molecular basis of activation of the arachidonate-regulated Ca2+ (ARC) channel, a store-independent Orai channel, by plasma membrane STIM1. Journal of Physiology 591(14): 3507-3523, 2013

A plasma membrane-targeted cytosolic domain of STIM1 selectively activates ARC channels, an arachidonate-regulated store-independent Orai channel. Channels 6(5): 370-378, 2012

Exploring the unique features of the ARC channel, a store-independent Orai channel. Channels 7(5): 364-373, 2013

The ARC channel--an endogenous store-independent Orai channel. Current Topics in Membranes 71: 125-148, 2013

The N-terminal domain of Orai3 determines selectivity for activation of the store-independent ARC channel by arachidonic acid. Channels 4(5): 398-410, 2010

Regulation of HERG potassium channel activation by protein kinase C independent of direct phosphorylation of the channel protein. Cardiovascular Research 59(1): 14-26, 2003

STIM2 protein mediates distinct store-dependent and store-independent modes of CRAC channel activation. Faseb Journal 22(3): 752-761, 2008

Phosphorylation-mediated structural changes within the SOAR domain of stromal interaction molecule 1 enable specific activation of distinct Orai channels. Journal of Biological Chemistry 293(9): 3145-3155, 2018

Targeting of an A kinase-anchoring protein, AKAP79, to an inwardly rectifying potassium channel, Kir2.1. Journal of Biological Chemistry 276(23): 20499-20505, 2001

Targeting of an A-kinase anchoring protein, AKAP79, to an inwardly rectifying potassium channel, murine Kir21. Journal of Physiology (Cambridge) 533P: 112P, 2001

A key role for STIM1 in store operated calcium channel activation in airway smooth muscle. Respiratory Research 7: 119, 2006

Arachidonate-regulated Ca2+-selective (ARC) channel activity is modulated by phosphorylation and involves an A-kinase anchoring protein. Journal of Physiology 567(Pt 3): 787-798, 2005

Structural Requirements of N- and C-Terminal Orai Strands to allow Maximal Store-Operated Ca2+ Current Activation by STIM1. Biophysical Journal 104(2): 615a-616a, 2013

Thapsigargin activates Ca²+ entry both by store-dependent, STIM1/Orai1-mediated, and store-independent, TRPC3/PLC/PKC-mediated pathways in human endothelial cells. Cell Calcium 49(2): 115-127, 2011

Selective activation of distinct Orai channels by STIM1. Cell Calcium 63: 40-42, 2017