Localization of a chemotactic domain in human thrombin.
The cyanogen bromide fragment CB67-129 of human prethrombin 1, corresponding to residues 54-116 of the thrombin B chain, is a potent chemotaxin for human peripheral blood monocytes and the murine macrophage like cell line, J774. Both of these cell types have been shown to respond chemotactically to alpha-thrombin and iPr2P-alpha-thrombin. Effective concentrations for stimulating directed cell movement with the fragment vary from 10(-11) to 10(-7) M. Moreover, CB67-129 and its parent protein compete for the same chemotactic receptor site. Fragment CB67-129, representing residues 54-116 of the human thrombin B chain sequence, contains a nine-residue insertion ("loop B") that is absent in homologous sequences derived from the closely related proteases chymotrypsin and trypsin. Unlike iPr2P-alpha-thrombin, iPr2P derivatives of these latter enzymes possess little or no chemotactic activity, suggesting a relationship between the insertion sequence and thrombin chemotactic activity. The loop B sequence is unique insofar as it contains all of the carbohydrate moieties known to reside in alpha-thrombin. However, chemotactic activity is only minimally reduced subsequent to hydrolysis by both neuraminidase and beta-galactosidase, indicating that receptor recognition and stimulated cell movement are mainly a function of structure of the cyanogen bromide derived fragment rather than of asparagine-linked carbohydrates.
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002633:Chemotaxis; D002634:Chemotaxis, Leukocyte; D003488:Cyanogen Bromide; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009000:Monocytes / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology; D011487:Protein Conformation; D013917:Thrombin / Q000502:physiology*
D010446:Peptide Fragments; D013917:Thrombin; D003488:Cyanogen Bromide