Enterokinase, the initiator of intestinal digestion, is a mosaic protease composed of a distinctive assortment of domains

@article{citeulike:3523357, abstract = {Enterokinase is a protease of the intestinal brush border that specifically cleaves the acidic propeptide from trypsinogen to yield active trypsin. This cleavage initiates a cascade of proteolytic reactions leading to the activation of many pancreatic zymogens. The full-length cDNA sequence for bovine enterokinase and partial cDNA sequence for human enterokinase were determined. The deduced amino acid sequences indicate that active two-chain enterokinase is derived from a single-chain precursor. Membrane association may be mediated by a potential signal-anchor sequence near the amino terminus. The amino terminus of bovine enterokinase also meets the known sequence requirements for protein N-myristoylation. The amino-terminal heavy chain contains domains that are homologous to segments of the low density lipoprotein receptor, complement components C1r and C1s, the macrophage scavenger receptor, and a recently described motif shared by the metalloprotease meprin and the Xenopus A5 neuronal recognition protein. The carboxyl-terminal light chain is homologous to the trypsin-like serine proteases. Thus, enterokinase is a mosaic protein with a complex evolutionary history. The amino acid sequence surrounding the amino terminus of the enterokinase light chain is ITPK-IVGG (human) or VSPK-IVGG (bovine), suggesting that single-chain enterokinase is activated by an unidentified trypsin-like protease that cleaves the indicated Lys-Ile bond. Therefore, enterokinase may not be the "first" enzyme of the intestinal digestive hydrolase cascade. The specificity of enterokinase for the DDDDK-I sequence of trypsinogen may be explained by complementary basic-amino acid residues clustered in potential S2-S5 subsites.}, author = {Kitamoto, Y. and Yuan, X. and Wu, Q. and Mccourt, D. W. and Sadler, J. E.}, citeulike-article-id = {3523357}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {16}, pages = {7588--7592}, posted-at = {2008-11-16 18:30:50}, priority = {2}, title = {Enterokinase, the initiator of intestinal digestion, is a mosaic protease composed of a distinctive assortment of domains}, url = {http://www.pnas.org/content/91/16/7588.abstract}, volume = {91}, year = {1994} }

TY - JOUR ID - citeulike:3523357 L3 - citeulike-article-id:3523357 N2 - Enterokinase is a protease of the intestinal brush border that specifically cleaves the acidic propeptide from trypsinogen to yield active trypsin. This cleavage initiates a cascade of proteolytic reactions leading to the activation of many pancreatic zymogens. The full-length cDNA sequence for bovine enterokinase and partial cDNA sequence for human enterokinase were determined. The deduced amino acid sequences indicate that active two-chain enterokinase is derived from a single-chain precursor. Membrane association may be mediated by a potential signal-anchor sequence near the amino terminus. The amino terminus of bovine enterokinase also meets the known sequence requirements for protein N-myristoylation. The amino-terminal heavy chain contains domains that are homologous to segments of the low density lipoprotein receptor, complement components C1r and C1s, the macrophage scavenger receptor, and a recently described motif shared by the metalloprotease meprin and the Xenopus A5 neuronal recognition protein. The carboxyl-terminal light chain is homologous to the trypsin-like serine proteases. Thus, enterokinase is a mosaic protein with a complex evolutionary history. The amino acid sequence surrounding the amino terminus of the enterokinase light chain is ITPK-IVGG (human) or VSPK-IVGG (bovine), suggesting that single-chain enterokinase is activated by an unidentified trypsin-like protease that cleaves the indicated Lys-Ile bond. Therefore, enterokinase may not be the "first" enzyme of the intestinal digestive hydrolase cascade. The specificity of enterokinase for the DDDDK-I sequence of trypsinogen may be explained by complementary basic-amino acid residues clustered in potential S2-S5 subsites. IS - 16 JF - Proceedings of the National Academy of Sciences of the United States of America EP - 7592 TI - Enterokinase, the initiator of intestinal digestion, is a mosaic protease composed of a distinctive assortment of domains VL - 91 SP - 7588 AU - Kitamoto, Y AU - Yuan, X AU - Wu, Q AU - Mccourt, DW AU - Sadler, JE PY - 1994//02/ UR - http://www.pnas.org/content/91/16/7588.abstract ER -