Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphorylation of skeletal muscle glycogen synthase catalyzed by a protein kinase is stimulated up to 10-fold by the calcium-dependent regulator (CDR) protein. Half-maximal stimulation requires about 1 microgram of CDR/ml. Phosphorylation by the CDR-dependent synthase kinase is more rapid at pH 8.6 than at pH 6.8 and is blocked by ethylene glycol bis(beta-aminoethyl-ether)N,N'-tetraacetic acid and trifuloperazine. Approximately 60 to 70% of the phosphate is incorporated into the trypsin-insensitive region of glycogen synthase resulting in conversion of the a form to the b form of the enzyme. The CDR-dependent synthase kinase is not myosin light chain kinase, as this enzyme does not phosphorylate glycogen synthase. Furthermore, synthase phosphorylation by the cAMP-dependent protein kinase catalytic subunit is not affected by CDR. The possibility that CDR-dependent synthase kinase may be phosphorylase kinase is being investigated.
 ...
PMID:Stimulation of glycogen synthase phosphorylation by calcium-dependent regulator protein. 10 93

A partially purified preparation (200-fold) of cAMP phosphodiesterase (PDE) was obtained from Mucor rouxii grown and extracted under conditions minimizing endogenous proteolysis. Four purification steps were applied: batch DEAE-Sepharose, DEAE-Sepharose chromatography, Sephadex G-150 super-fine gel filtration and sucrose gradient centrifugation. The final PDE preparation was activatable by cAMP-dependent phosphorylation and controlled trypsin treatment. A careful correlation of protein patterns with PDE activity was done throughout the whole procedure by analyzing the active fractions of each step by mini-polyacrylamide non-denaturing gel electrophoresis. The final preparation displayed four major protein bands, none of which corresponded to PDE, although PDE activity comigrated with two of them. Some properties of this preparation were studied. Vmax increased around 10-15 fold by activation of PDE by phosphorylation or proteolysis; Km values were unaffected. PDE had Stokes radius of 3.5 nm, sedimentation coefficient of 4.3 S and molecular weight of 70,000 daltons. The treatment of sucrose gradient fractions with [gamma-32P] ATP and cAMP-dependent protein kinase catalytic subunit and further analysis through minigels showed that none of the visible bands was phosphorylated, and that among the four phosphorylated bands there was one that cosedimented and comigrated with PDE activity. Trypsin treatment of the phosphorylated samples removed the label but did not modify the staining pattern.
 ...
PMID:Further studies on the phosphorylation-regulated cAMP-phosphodiesterase from the dimorphic fungus Mucor rouxii. 285 14

Epidermal growth factor (EGF)-dependent transfer of radiolabeled phosphate from [gamma-32P]ATP to 160-kDa EGF receptor solubilized from human epidermoid carcinoma A431 cell surface membranes was stimulated up to 3-fold by addition of 3',5'-cAMP and purified cAMP-dependent protein kinase. Phosphorylation of EGF receptors was stimulated to the same extent when cAMP-dependent protein kinase catalytic subunit was substituted for 3',5'-cAMP and cAMP-dependent protein kinase. Phosphoamino acid analysis revealed that the extent of phosphorylation of EGF receptor at tyrosine residues was the same regardless of whether cAMP-dependent protein kinase catalytic subunit was present in or omitted from the system. Increased EGF receptor phosphorylation occurring in response to cAMP-dependent protein kinase catalytic subunit was accounted for by phosphorylation at serine or threonine residues. In samples phosphorylated in the presence of cAMP-dependent protein kinase catalytic subunit, phosphate was present in tyrosine, serine, and threonine in a ratio of 32:60:8. Two-dimensional mapping of radiolabeled phosphopeptides produced from EGF receptors by digestion with trypsin revealed the generation of one additional major phosphoserine-containing peptide when cAMP-dependent protein kinase was present with EGF in the EGF receptor kinase system. Degradation of 160-kDa EGF receptors to a 145-kDa form by purified Ca2+-activated neutral protease produced a 145-kDa fragment with phosphoserine content increased over that present initially in the 160-kDa precursor.
 ...
PMID:cAMP-dependent protein kinase stimulates epidermal growth factor-dependent phosphorylation of epidermal growth factor receptors. 632 45