Identification of the sites in myelin basic protein that are phosphorylated by meiosis-activated protein kinase p44mpk.
Myelin basic protein serves as a convenient substrate for detection of a 44 kDa protein-serine/threonine kinase (p44mpk) that is activated near the time of germinal vesicle breakdown in maturing echinoderm and amphibian oocytes. In vitro phosphorylation by purified p44mpk from sea star oocytes was primarily on threonine residues on a single tryptic peptide of bovine brain myelin basic protein. Amino acid composition analysis of the isolated posphopeptide revealed that it was rich in proline residues. Automated solid-phase sequencing by Edman degradation identified the major site as Thr-97 in the sequence NIVTPRTPPPSQGK, which corresponds to residues 91-104 in bovine brain myelin basic protein. Thr-94 was also phosphorylated by p44mpk to a very minor extent.
Biomedical Research Centre, University of British Columbia, Vancouver, Canada.
J S
JS
Sanghera
R
R
Aebersold
H D
HD
Morrison
E J
EJ
Bures
S L
SL
Pelech
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D008540:Meiosis; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D008970:Molecular Weight; D004676:Myelin Basic Protein / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D014357:Trypsin
D000596:Amino Acids; D004676:Myelin Basic Protein; D010446:Peptide Fragments; D010748:Phosphopeptides; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D014357:Trypsin