Open AccessA novel form of gastric inhibitory polypeptide (GIP) isolated from bovine intestine using a radioreceptor assay
Author(s) -
CARLQUIST Mats,
MALETTI Maura,
JÖRNVALL Hans,
MUTT Viktor
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08595.x
Subject(s) - gastric inhibitory polypeptide , enteropeptidase , biochemistry , exopeptidase , protease , chemistry , microbiology and biotechnology , amino acid , proteolysis , biology , enzyme , hormone , glucagon , fusion protein , gene , recombinant dna
A novel form of gastric inhibitory polypeptide (GIP), later also referred to as glucose‐dependent insulinotropic polypeptide, has been isolated from bovine upper intestine. The purification was monitored by a recently developed radioreceptor assay, specific for GIP, using membrane preparations from hamster β‐cell tumors. A combination of ion‐exchange and reverse‐phase high‐performance liquid chromatography was used in the isolation which resulted in homogeneous bovine GIP. Bovine GIP is, like porcine GIP, composed of 42 amino acid residues. The sequence is: Tyr‐Ala‐Glu‐Gly‐Thr‐Phe‐Ile‐Ser‐Asp‐Tyr‐Ser‐Ile‐Ala‐Met‐Asp‐Lys‐Ile‐Arg‐Gln‐Gln‐Asp‐Phe‐Val‐Asn‐Trp‐Leu‐Leu‐Ala‐Gln‐Lys‐Gly‐Lys‐Lys‐Ser‐Asp‐Trp‐Ile‐His‐Asn‐Ile‐Thr‐Gln, which differs from that of the previously characterized porcine GIP by having isoleucine instead of lysine at position 37. Upon proteolytic digestion of GIP with the staphylococcal V8 protease and with enterokinase, two fragments are formed in each case, corresponding to GIP 1‐3 , GIP 4‐42 , and GIP 1‐16 , GIP 17‐42 , respectively.