Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complete primary structure of inhibitor-2, a specific inhibitor of protein phosphatase-1, has been determined. The protein consists of a single polypeptide chain of 203 residues, and has a relative molecular mass of 22835 Da. This molecular mass is significantly lower than earlier estimates based on sodium dodecyl sulphate polyacrylamide gel electrophoresis. The threonyl residue phosphorylated by glycogen synthase kinase-3 is located at position 72. The molecule is very hydrophilic, lacks cysteine residues and the single tryptophanyl and phenylalanyl residues are at positions 46 and 139, respectively. The N-terminal alanyl residue is N-acetylated. Digestion with Staphylococcus aureus V8 proteinase, trypsin, or cleavage with cyanogen bromide, destroyed the biological activity of inhibitor-2, demonstrating that many large fragments (e.g. 1-49, 49-92, 67-101, 108-134, 142-182 and 163-197) are inactive. Digestion with clostripain generated a peptide comprising residues 25-114 which retained 2% of the inhibitory potency of the parent molecule. There is no sequence homology between inhibitor-2 and inhibitor-1.
 ...
PMID:The protein phosphatases involved in cellular regulation. Primary structure of inhibitor-2 from rabbit skeletal muscle. 351 70

A membranal proteinase from brush-border epithelial cells of the rat small intestine was shown to bring about a restricted and limited degradation of the free catalytic subunit (C) of cyclic AMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) with concomitant inactivation of the kinase. This membranal proteinase exhibits a remarkable specificity. (i) It degrades C in its native conformation, but not after it has been heat-denatured. (ii) The degradation of C (Mr 40,000) does not proceed further, once a distinct clipped product (Mr 34,000) is formed. (iii) The undissociated ("stored") form of the enzyme (R2C2) is not attacked by the membranal proteinase, preserving both its potential catalytic activity and its molecular integrity. Only upon addition of cyclic AMP to release free C does the proteinase attack it. (iv) The membranal proteinase does not degrade the regulatory subunit (R), released by cyclic AMP from R2C2, although R is quite susceptible to degradation by other proteolytic enzymes. None of these features of the membranal proteinase could be reproduced with trypsin, chymotrypsin, clostripain, or papain. The specific, restricted, and limited action of this membranal enzyme raises the possibility that it may have a distinct physiological assignment associated with the bioregulation of cyclic AMP-dependent protein kinase.
 ...
PMID:Degradative inactivation of cyclic AMP-dependent protein kinase by a membranal proteinase is restricted to the free catalytic subunit in its native conformation. 626 95

Collagenase preparations (a mixture of enzymes including collagenase, clostripain, and a casein-degrading protease) degraded the beta subunit (Mr = 95,000) of the purified insulin receptor into fragments of Mr less than 15,000, without degrading the alpha subunit. The resulting beta-digested insulin receptor preparations were found to bind insulin as well as control insulin receptor, as assessed by either cross-linking of 125I-insulin to the digested receptor or by separating insulin bound to receptor from free insulin by high performance liquid chromatography. Moreover, the beta-digested insulin receptor preparations were still precipitated by a monoclonal antibody directed against the insulin-binding site. In contrast, the beta-digested insulin receptor lacked protein kinase activity since it no longer phosphorylated either itself, or an exogenous substrate, calf thymus histone. These results support the identification of the beta subunit of the insulin receptor as a protein kinase.
 ...
PMID:Preferential degradation of the beta subunit of purified insulin receptor. Effect on insulin binding and protein kinase activities of the receptor. 631 28

19S Thyroglobulin (Tg), a dimeric glycoprotein with an M(r) of 660,000, was extracted from rat, bovine, and human (goitrous) thyroid tissues, as well as from culture medium of FRTL5 rat thyroid cells. Subjected to rigorous purification procedures, all Tg preparations showed a protein kinase activity that is able to phosphorylate serine residues in vitro. Further characterization of this enzymatic activity revealed that Tg has the specificities of a protein kinase A when Kemptide was used as specific substrate and after analysis of cAMP-stimulated phosphotransferase activity in all Tg preparations tested. Furthermore, Tg contains a specific and saturable ATP binding site, as evidenced by specific binding with the ATP affinity analog p-fluorosulfonylbenzoyl 5'-p-adenosine (FSO2BzAdo). Limited proteolysis of FSO2[14C]BzAdo-labeled human goiter Tg with clostripain gave rise to a M(r) 64,000 amino terminal polypeptide carrying almost all of the label. The analysis of this fragment revealed two sequences that may play an analogous phosphate-loop (P-loop) function, even though their primary sequences differ slightly from the classical A consensus sequence or P-loop. The ATP binding site of Tg may be functionally associated with the presence of a protein kinase A phosphorylating activity linked to the Tg itself, because the addition of the analog is able to inhibit the enzymatic activity in a dose-dependent fashion. Contamination with non-Tg phosphorylase cannot be ruled out at present, even though the amount of ATP that Tg was able to bind did not significantly change during the various purification steps. Together these findings favor the hypothesis that the Tg molecule contains a protein kinase activity that is capable of autophosphorylation.
 ...
PMID:Evidence that thyroglobulin has an associated protein kinase activity correlated with the presence of an adenosine triphosphate binding site. 762 48

Human placental 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (HP2K) was phosphorylated by incubation with [gamma-32P]MgATP and cyclic AMP-dependent protein kinase (PKA) or protein kinase C (PKC). Approximately 0.8 mol of phosphate per mol subunit of HP2K was incorporated by either PKA or PKC. However, with additional incubation with PKA following incubation with PKC or vice versa, no additional phosphate was incorporated into the HP2K. The phosphorylation sites for the two protein kinases were identified by peptide mapping and microsequencing following digestion of phosphorylated-HP2K with clostripain. Evidence is also suggested for a common phosphorylation site (Ser-460) for PKA and PKC.
 ...
PMID:A common phosphorylation site for cyclic AMP-dependent protein kinase and protein kinase C in human placental 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase. 983 40

In response to extracellular signals, G protein-coupled receptors (GPCRs) catalyze guanine nucleotide exchange on Galpha subunits, enabling both activated Galpha and Gbetagamma subunits to target downstream effector enzymes. One target of Gbetagamma is G protein-coupled receptor kinase 2 (GRK2), an enzyme that initiates homologous desensitization by phosphorylating activated GPCRs. GRK2 consists of three distinct domains: an RGS homology (RH) domain, a protein kinase domain, and a pleckstrin homology (PH) domain, through which it binds Gbetagamma. The crystal structure of the GRK2-Gbetagamma complex revealed that the domains of GRK2 are intimately associated and left open the possibility for allosteric regulation by Gbetagamma. In this paper, we report the 4.5 A structure of GRK2, which shows that the binding of Gbetagamma does not induce large domain rearrangements in GRK2, although small rotations of the RH and PH domains relative to the kinase domain are evident. Mutation of residues within the larger domain interfaces of GRK2 generally leads to diminished expression and activity, suggesting that these interfaces are important for stability and remain intact upon activation of GRK2. Geranylgeranylated Gbetagamma, but not a soluble mutant of Gbetagamma, protects GRK2 from clostripain digestion at a site within its kinase domain that is 80 A away from the Gbetagamma binding site. Equilibrium ultracentrifugation experiments indicate that neither abnormally large detergent micelles nor protein oligomerization can account for the observed protection. The Gbetagamma-mediated binding of GRK2 to CHAPS micelles or lipid bilayers therefore appears to rigidify the kinase domain, perhaps by encouraging stable contacts between the RH and kinase domains.
 ...
PMID:The role of G beta gamma and domain interfaces in the activation of G protein-coupled receptor kinase 2. 1586 41