Molecular cloning, characterization, and expression of a cDNA encoding the '80- to 87-kDa' myristoylated alanine-rich C kinase substrate: A major cellular substrate for protein kinase C

We isolated and sequenced a cDNA clone encoding the bovine '80- to 87-kDa' protein, a major cellular substrate for protein kinase C. An open reading frame of 1005 base pairs predicted a protein of 335 amino acids (M(r), 31,949). Despite this predicted size, the protein migrated on SDS/polyacrylamide gels with an apparent molecular weight of 80-87,000 after expression of the cDNA in cells lacking the protein. It was highly enriched in alanine (28.4 mol %), contained an amino-terminal myristoylation consensus sequence, and included a 25-residue basic domain containing the known protein kinase C phosphorylation sites. Two mRNA species (2.6 and 4.4 kilobases) were mostly highly expressed in brain, spinal cord, spleen, and lung, in parallel with the distribution of immunoreactive protein. Genomic blot analysis indicated the likelihood of a single gene coding for this mRNA. We propose the name myristoylated alanine-rich C kinase substrate (MARCKS) for this protein.