Metastasis-associated Mts1 (S100A4) protein modulates protein kinase C phosphorylation of the heavy chain of nonmuscle myosin.
Mts1 protein (S100A4 according to a new classification) has been implicated in the formation of the metastatic phenotype via regulation of cell motility and invasiveness. Previously we have demonstrated that Mts1 protein interacted with the heavy chain of nonmuscle myosin in a calcium-dependent manner. To elucidate the role of the Mts1-myosin interaction, we mapped the Mts1-binding region on the myosin heavy chain molecule. We prepared proteolytically digested platelet myosin and a series of overlapped myosin heavy chain protein fragments and used them in a blot overlay with Mts1 protein. Here we report that the Mts1-binding site is located within a 29-amino acid region, at the C-terminal end of the myosin heavy chain (between 1909-1937 amino acids). Two-dimensional phosphopeptide analysis showed that Mts1 protein inhibits protein kinase C phosphorylation of the platelet myosin heavy chain at Ser-1917. We hypothesize that Mts1 protein regulates cytoskeletal dynamics of the metastatic cells through modulation of the myosin phosphorylation by protein kinase C in calcium-dependent fashion.
Kriajevska
M
M
Danish Cancer Society, Division of Cancer Biology, Strandboulevarden 49, DK-2100 Copenhagen, Denmark.
Tarabykina
S
S
Bronstein
I
I
Maitland
N
N
Lomonosov
M
M
Hansen
K
K
Georgiev
G
G
Lukanidin
E
E
D001665:Binding Sites; D001792:Blood Platelets / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D006801:Humans; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D012516:Osteosarcoma; D010446:Peptide Fragments / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; D014407:Tumor Cells, Cultured
D002135:Calcium-Binding Proteins; D010446:Peptide Fragments; D010748:Phosphopeptides; D011994:Recombinant Proteins; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; C077591:S100A4 protein, human; D011493:Protein Kinase C; D018995:Myosin Heavy Chains; D002118:Calcium