Biomedical subjects

L K McCall

Publications and source records attributed to L K McCall.

6 recordsLinked to original sources

PubMed1994

Phosphorylation of endogenous substrates of yeast protein kinase C regulated by lipid-triton micelles.

In the DE-52 fraction 19 of the crude cytosolic extract of Saccharomyces cerevisiae, the 31-kDa endogenous substrate(s) of protein kinase C were detected by SDS-polyacrylamide gel electrophoresis and autoradiography. Phosphorylation of the substrate(s) depended on Ca2+, phosphatidylserine and diacylglycerol. It was also enhanced by phosphatidylinositol, phosphatidylethanolamine and phosphatidylglycerol (dioleoyl), but inhibited by arachidonic acid and sphingosine.

Arachidonic Acid↗

PubMed1994

Dual modulation of the phosphorylation of endogenous yeast proteins by arachidonic acid and phosphatidylinositol.

Phosphorylation of endogenous yeast substrates in DE-52 fractions were analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. In fractions 29 and 45, phosphatidylinositol inhibited the phosphorylation of multiple peptides with a wide range of molecular mass whereas it enhanced the phosphorylation of peptides smaller than 14 kD. Similar dual modulation of the phosphorylation by arachidonic acid was observed in fraction 37 which also contained potent phosphatidylserine-activating protein kinase C.

Arachidonic Acid↗

PubMed1994

Enhanced phosphorylation of yeast endogenous substrates by phosphatidylglycerol (dioleoyl) and phosphatidylinositol.

Protein kinases and their endogenous substrates from the crude cytosolic extract of Saccharomyces cerevisiae were coeluted in the fraction 13 on DE-52 column chromatography. Analyses of SDS-polyacrylamide gel electrophoresis and autoradiography revealed that the peptides between 14 and 34 kDa were the major phosphorylated substrates. In the presence of Ca2+ and Mg2+, the phosphorylation was suppressed strongly by the regulatory subunit of cAMP-dependent protein kinase and slightly by oleic acid, whereas it was augmented appreciably by phosphatidylglycerol (dioleoyl) and phosphatidylinositol.

Adenosine Triphosphate↗

PubMed1993

Modulation of the activity of calpain II by phosphorylation--changes in the proteolysis of cyclic AMP-dependent protein kinase (peak II, DEAE).

The proteolysis of the 32P-labeled holoenzyme of cyclic AMP-dependent protein kinase (A-PKII:DEAE, peak II fraction) was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The contaminants of the A-PKII and calpain II apparently did not interfere with the accuracy of this highly sensitive analysis. Phosphorylation of calpain II by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) greatly enhanced the proteolysis of A-PKII, whereas phosphorylation by protein kinase C (PK-C) or cyclic GMP-dependent protein kinase (G-PK) slightly altered the proteolysis.

Calpain↗

PubMed1993

Regulation of the phosphorylation of histones and glycogen synthase.

The phosphorylation of histones and glycogen synthase by protein kinases was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The phosphorylation of histone III-S by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) or cGMP-dependent protein kinase (G-PK) was inhibited by archidonic acid, sphingosine and staurosporine. Using the catalytic subunit of A-PK, the phosphorylation of histone VIII-S was inhibited by Ca2+, arachidonic acid and staurosporine; the phosphorylation of histone II-S was inhibited by phosphatidyl ethanolamine, phosphatidyl inositol, arachidonic acid and staurosporine; and the phosphorylation of glycogen synthase was inhibited by arachidonic acid and staurosporine. After being phosphorylated by the catalytic subunit of A-PK, calpain II with 4 microM Ca2+ was less effective in degrading histone III-S, which had been prephosphorylated by PK-C.

AMP-Activated Protein Kinases↗

PubMed1992

Regulation of Staphylococcus protease using complement, interferon and immunoglobulin as substrates.

The effects of various agents on the cleavage of serum albumin, interferon, immunoglobulin and complement component C1q by the extracellular protease from Staphylococcus aureus were analysed by SDS-polyacrylamide gel electrophoresis. Arachidonic acid moderately stimulated the proteolysis of serum albumin, interferon and complement component. Phosphatidic acid effectively enhanced the proteolysis of serum albumin and IgG, whereas it inhibited the cleavage of IgM. The proteolysis of IgG was appreciably enhanced by sphingosine. In contrast, phosphatidyl choline and phosphatidyl glycerol were shown to have an inhibitory effect on the proteolysis of IgG and IgM. Phosphatidyl serine, phosphatidyl inositol and phosphatidyl ethanolamine also inhibited the proteolysis of IgG. The failure of any of these agents to exert a persistent effect on the cleavage of all substrates, revealed the complexity of the interactions among the agent, the substrate and the protease.

Complement C1q↗