Serine/threonine-protein phosphatase 2B catalytic subunit alpha isoform - Q08209 (PP2BA_HUMAN)


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Calcium-dependent, calmodulin-stimulated protein phosphatase which plays an essential role in the transduction of intracellular Ca(2+)-mediated signals (PubMed:15671020, PubMed:18838687, PubMed:19154138, PubMed:23468591). Many of the substrates contain a PxIxIT motif and/or a LxVP motif (PubMed:17498738, PubMed:17502104, PubMed:23468591, PubMed:27974827, PubMed:22343722). In response to increased Ca(2+) levels, dephosphorylates and activates phosphatase SSH1 which results in cofilin dephosphorylation (PubMed:15671020). In response to increased Ca(2+) levels following mitochondrial depolarization, dephosphorylates DNM1L inducing DNM1L translocation to the mitochondrion (PubMed:18838687). Dephosphorylates heat shock protein HSPB1 (By similarity). Dephosphorylates and activates transcription factor NFATC1 (PubMed:19154138). In response to increased Ca(2+) levels, regulates NFAT-mediated transcription probably by dephosphorylating NFAT and promoting its nuclear translocation (PubMed:26248042). Dephosphorylates and inactivates transcription factor ELK1 (PubMed:19154138). Dephosphorylates DARPP32 (PubMed:19154138). May dephosphorylate CRTC2 at 'Ser-171' resulting in CRTC2 dissociation from 14-3-3 proteins (PubMed:30611118). UniProt
Catalytic Activity
H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate UniProt
Pathway Maps
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Subunit Structure
Forms a complex composed of a calmodulin-dependent catalytic subunit (also known as calcineurin A) and a regulatory Ca(2+)-binding subunit (also known as calcineurin B) (PubMed:8524402, PubMed:12218175, PubMed:12357034, PubMed:17498738, PubMed:22343722, PubMed:23468591, PubMed:27974827). There are three catalytic subunits, each encoded by a separate gene (PPP3CA, PPP3CB, and PPP3CC) and two regulatory subunits which are also encoded by separate genes (PPP3R1 and PPP3R2). In response to an increase in Ca(2+) intracellular levels, forms a complex composed of PPP3CA/calcineurin A, calcineurin B and calmodulin (By similarity). Interacts (via calcineurin B binding domain) with regulatory subunit PPP3R1/calcineurin B (PubMed:8524402, PubMed:12218175, PubMed:12357034, PubMed:17498738, PubMed:22343722, PubMed:23468591, PubMed:27974827). Interacts (via calmodulin-binding domain) with CALM1/calmodulin; the interaction depends on calmodulin binding to Ca(2+) (PubMed:18384083, Ref.30, PubMed:19404396, PubMed:25144868). Forms a complex composed of MYOZ2 and ACTN1 (By similarity). Within the complex interacts with MYOZ2 (PubMed:11114196). Interacts with MYOZ1 (PubMed:11114196). Interacts with MYOZ3 (PubMed:11842093). Interacts with CIB1; the interaction increases upon cardiomyocyte hypertrophy (By similarity). Interacts with CHP1 and CHP2 (By similarity). Interacts with CRTC1 (PubMed:30611118). Interacts with CRTC2 (PubMed:15454081, PubMed:30611118). Interacts with DNM1L; the interaction dephosphorylates DNM1L and promotes its translocation to mitochondria (PubMed:18838687). Interacts with CMYA5; this interaction represses calcineurin activity in muscle (By similarity). Interacts (constitutively active form) with SYNPO2 (PubMed:17923693). Interacts with scaffold protein AKAP5 (via IAIIIT motif); the interaction recruits PPP3CA to the plasma membrane following L-type Ca(2+)-channel activation (PubMed:22343722). Interacts with NFATC2 (PubMed:26248042). Interacts with RCAN3 (PubMed:26248042). Interacts with PPIA (PubMed:12218175, PubMed:12357034). Interacts with RCAN1 (PubMed:12809556). Interacts with UNC119 (By similarity). UniProt
Possible isomerization of Pro-309 within the SAPNY motif triggers a conformation switch which affects the organization and thus accessibility of the active site and the substrate binding region (PxIxIF motif). The trans- to cis-transition may favor calcineurin A activation and substrate binding. The reverse cis- to trans-transition may be enhanced by peptidyl-prolyl isomerases such as PPIA. UniProt
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