2qcs
From Proteopedia
A complex structure between the Catalytic and Regulatory subunit of Protein Kinase A that represents the inhibited state
Structural highlights
FunctionKAPCA_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] 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 PubMedProtein kinase A (PKA) holoenzyme is one of the major receptors for cyclic adenosine monophosphate (cAMP), where an extracellular stimulus is translated into a signaling response. We report here the structure of a complex between the PKA catalytic subunit and a mutant RI regulatory subunit, RIalpha(91-379:R333K), containing both cAMP-binding domains. Upon binding to the catalytic subunit, RI undergoes a dramatic conformational change in which the two cAMP-binding domains uncouple and wrap around the large lobe of the catalytic subunit. This large conformational reorganization reveals the concerted mechanism required to bind and inhibit the catalytic subunit. The structure also reveals a holoenzyme-specific salt bridge between two conserved residues, Glu261 and Arg366, that tethers the two adenine capping residues far from their cAMP-binding sites. Mutagenesis of these residues demonstrates their importance for PKA activation. Our structural insights, combined with the mutagenesis results, provide a molecular mechanism for the ordered and cooperative activation of PKA by cAMP. PKA-I holoenzyme structure reveals a mechanism for cAMP-dependent activation.,Kim C, Cheng CY, Saldanha SA, Taylor SS Cell. 2007 Sep 21;130(6):1032-43. PMID:17889648[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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