| Structural highlights
3idb is a 2 chain structure with sequence from Buffalo rat and Lk3 transgenic mice. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , |
| NonStd Res: | , |
| Related: | 3idc, 1cx4, 1rgs, 2qcs, 2qvs |
| Gene: | Pkaca, Prkaca (LK3 transgenic mice), Prkar2b (Buffalo rat) |
| Activity: | cAMP-dependent protein kinase, with EC number 2.7.11.11 |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Function
[KAPCA_MOUSE] Phosphorylates a large number of substrates in the cytoplasm and the nucleus. Regulates the abundance of compartmentalized pools of its regulatory subunits through phosphorylation of PJA2 which binds and ubiquitinates these subunits, leading to their subsequent proteolysis. Phosphorylates CDC25B, ABL1, NFKB1, CLDN3, PSMC5/RPT6, PJA2, RYR2, RORA, TRPC1 and VASP. RORA is activated by phosphorylation. Required for glucose-mediated adipogenic differentiation increase and osteogenic differentiation inhibition from osteoblasts. Involved in the regulation of platelets in response to thrombin and collagen; maintains circulating platelets in a resting state by phosphorylating proteins in numerous platelet inhibitory pathways when in complex with NF-kappa-B (NFKB1 and NFKB2) and I-kappa-B-alpha (NFKBIA), but thrombin and collagen disrupt these complexes and free active PRKACA stimulates platelets and leads to platelet aggregation by phosphorylating VASP. Prevents the antiproliferative and anti-invasive effects of alpha-difluoromethylornithine in breast cancer cells when activated. RYR2 channel activity is potentiated by phosphorylation in presence of luminal Ca(2+), leading to reduced amplitude and increased frequency of store overload-induced Ca(2+) release (SOICR) characterized by an increased rate of Ca(2+) release and propagation velocity of spontaneous Ca(2+) waves, despite reduced wave amplitude and resting cytosolic Ca(2+). TRPC1 activation by phosphorylation promotes Ca(2+) influx, essential for the increase in permeability induced by thrombin in confluent endothelial monolayers. PSMC5/RPT6 activation by phosphorylation stimulates proteasome. Regulates negatively tight junction (TJs) in ovarian cancer cells via CLDN3 phosphorylation. NFKB1 phosphorylation promotes NF-kappa-B p50-p50 DNA binding. Involved in embryonic development by down-regulating the Hedgehog (Hh) signaling pathway that determines embryo pattern formation and morphogenesis. Isoform 2 phosphorylates and activates ABL1 in sperm flagellum to promote spermatozoa capacitation. Prevents meiosis resumption in prophase-arrested oocytes via CDC25B inactivation by phosphorylation. May also regulate rapid eye movement (REM) sleep in the pedunculopontine tegmental (PPT).[1] [2] [3] [KAP3_RAT] Regulatory subunit of the cAMP-dependent protein kinases involved in cAMP signaling in cells. Type II regulatory chains mediate membrane association by binding to anchoring proteins, including the MAP2 kinase.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The cAMP-dependent protein kinase catalytic (C) subunit is inhibited by two classes of functionally nonredundant regulatory (R) subunits, RI and RII. Unlike RI subunits, RII subunits are both substrates and inhibitors. Because RIIbeta knockout mice have important disease phenotypes, the RIIbeta holoenzyme is a target for developing isoform-specific agonists and/or antagonists. We also know little about the linker region that connects the inhibitor site to the N-terminal dimerization domain, although this linker determines the unique globular architecture of the RIIbeta holoenzyme. To understand how RIIbeta functions as both an inhibitor and a substrate and to elucidate the structural role of the linker, we engineered different RIIbeta constructs. In the absence of nucleotide, RIIbeta(108-268), which contains a single cyclic nucleotide binding domain, bound C subunit poorly, whereas with AMP-PNP, a non-hydrolyzable ATP analog, the affinity was 11 nM. The RIIbeta(108-268) holoenzyme structure (1.62 A) with AMP-PNP/Mn(2+) showed that we trapped the RIIbeta subunit in an enzyme:substrate complex with the C subunit in a closed conformation. The enhanced affinity afforded by AMP-PNP/Mn(2+) may be a useful strategy for increasing affinity and trapping other protein substrates with their cognate protein kinase. Because mutagenesis predicted that the region N-terminal to the inhibitor site might dock differently to RI and RII, we also engineered RIIbeta(102-265), which contained six additional linker residues. The additional linker residues in RIIbeta(102-265) increased the affinity to 1.6 nM, suggesting that docking to this surface may also enhance catalytic efficiency. In the corresponding holoenzyme structure, this linker docks as an extended strand onto the surface of the large lobe. This hydrophobic pocket, formed by the alphaF-alphaG loop and conserved in many protein kinases, also provides a docking site for the amphipathic helix of PKI. This novel orientation of the linker peptide provides the first clues as to how this region contributes to the unique organization of the RIIbeta holoenzyme.
Novel isoform-specific interfaces revealed by PKA RIIbeta holoenzyme structures.,Brown SH, Wu J, Kim C, Alberto K, Taylor SS J Mol Biol. 2009 Nov 13;393(5):1070-82. Epub 2009 Sep 11. PMID:19748511[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Nolan MA, Babcock DF, Wennemuth G, Brown W, Burton KA, McKnight GS. Sperm-specific protein kinase A catalytic subunit Calpha2 orchestrates cAMP signaling for male fertility. Proc Natl Acad Sci U S A. 2004 Sep 14;101(37):13483-8. Epub 2004 Aug 31. PMID:15340140 doi:10.1073/pnas.0405580101
- ↑ Pirino G, Wescott MP, Donovan PJ. Protein kinase A regulates resumption of meiosis by phosphorylation of Cdc25B in mammalian oocytes. Cell Cycle. 2009 Feb 15;8(4):665-70. Epub 2009 Feb 14. PMID:19223768
- ↑ Baker MA, Hetherington L, Curry B, Aitken RJ. Phosphorylation and consequent stimulation of the tyrosine kinase c-Abl by PKA in mouse spermatozoa; its implications during capacitation. Dev Biol. 2009 Sep 1;333(1):57-66. doi: 10.1016/j.ydbio.2009.06.022. Epub 2009, Jun 26. PMID:19560455 doi:10.1016/j.ydbio.2009.06.022
- ↑ Brown SH, Wu J, Kim C, Alberto K, Taylor SS. Novel isoform-specific interfaces revealed by PKA RIIbeta holoenzyme structures. J Mol Biol. 2009 Nov 13;393(5):1070-82. Epub 2009 Sep 11. PMID:19748511 doi:10.1016/j.jmb.2009.09.014
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