title: Amino acid sequence of rat mast cell protease I (chymase).
abstract: The amino acid sequence has been determined for rat mast cell protease I (RMCP I), a product of peritoneal mast cells. The active enzyme contains 227 residues, including three corresponding to the catalytic triad characteristic of serine protease (His-57, Asp-102, and Ser-195 in chymotrypsin). A computer search for homology indicates 73% and 33% sequence identity of RMCP I with rat mast cell protease II from mucosal mast cells and bovine chymotrypsin A, respectively. When the structure of RMCP I is compared to those of cathepsin G from human neutrophils and two proteases expressed in activated lymphocytes, 48-49% of the sequences are identical in each case. RMCP I has six half-cystine residues at the same positions as in RMCP II, cathepsin G, and the two lymphocyte proteases, suggesting disulfide pairs identical with those reported for RMCP II. A disulfide bond near the active site seryl residue and substrate binding site, present in pancreatic and plasma serine proteases, is not found in RMCP I or in the other cellular proteases. These results indicate that RMCP I and other chymotrypsin-like proteases of granulocyte and lymphocyte origin are more closely related to each other than to the pancreatic or plasma serine proteases.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D053818:Chymases; D008239:Lysine; D008407:Mast Cells / Q000201:enzymology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D051381:Rats; D012697:Serine Endopeptidases / Q000302:isolation & purification
chemical_list: D010446:Peptide Fragments; D012697:Serine Endopeptidases; D053818:Chymases; D008239:Lysine