Identification of the protein kinase C phosphorylation site in neuromodulin

Journal Article · Tue Mar 06 04:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00461a017· OSTI ID:6940703

Apel, E D; Byford, M F; Au, D; Walsh, K A; Storm, D R ^[1]

---

1. Univ. of Washington, Seattle (USA)

Neuromodulin (P-57, GAP-43, B-50, F-1) is a neurospecific calmodulin binding protein that is phosphorylated by protein kinase C. Phosphorylation by protein kinase C has been shown to abolish the affinity of neuromodulin for calmodulin and the authors have proposed that the concentration of free CaM in neurons may be regulated by phosphorylation and dephosphorylation of neuromodulin. The purpose of this study was to identify the protein kinase C phosphorylation site(s) in neuromodulin using recombinant neuromodulin as a substrate. Toward this end, it was demonstrated that recombinant neuromodulin purified from Escherichia coli and bovine neuromodulin were phosphorylated with similar K{sub m} values and stoichiometries and that protein kinase C mediated phosphorylation of both proteins abolished binding to calmodulin-Sepharose. Recombinant neuromodulin was phosphorylated by using protein kinase C and ({gamma}-{sup 32}P)ATP and digested with trypsin, and the resulting peptides were separated by HPLC. Only one {sup 32}P-labeled tryptic peptide was generated from phosphorylated neuromodulin. They conclude that serine-41 is the protein kinase C phosphorylation site of neuromodulin and that phosphorylation of this amino acid residue blocks binding of calmoculin to neuromodulin. The proximity of serine-41 to the calmodulin binding domain in neuromodulin very likely explains the effect of phosphorylation on the affinity of neuromodulin for calmodulin.

• OSTI ID: 6940703
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:9; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
AMINO ACIDS
ANIMALS
ATP
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CATTLE
CHEMICAL REACTIONS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ELECTROPHORESIS
ENZYMES
ESCHERICHIA COLI
HYDROXY ACIDS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIQUID COLUMN CHROMATOGRAPHY
MAMMALS
MEMBRANE PROTEINS
MICROORGANISMS
MOLECULAR STRUCTURE
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RUMINANTS
SEPARATION PROCESSES
SERINE
STOICHIOMETRY
TRANSFERASES
VERTEBRATES