Isolation and sequence determination of two N-terminal fragments of islet amyloid polypeptide in rat pancreas.
Using a highly sensitive and specific radioimmunoassay (RIA) for the N-terminal hexadecapeptide of islet amyloid polypeptide (IAPP), we isolated two N-terminal fragments of IAPP from rat pancreas. They were identified as IAPP(1-16) and IAPP(1-17) by amino acid sequencing. The two fragments were also found in rat plasma. IAPP(1-37) was the major molecular form of rat IAPP, IAPP(1-16) and IAPP(1-17) accounting for 6.0% and 32.3% of the immunoreactivity for the N-terminal region of the peptide in pancreata of normally fed rats. In human pancreas, the N-terminal fragments of IAPP were not present, indicating that the processing of IAPP in the pancreas differs between human and rat. Food deprivation increased the molar ratios of IAPP(1-16) and IAPP(1-17) to IAPP(1-37) in comparison to values for fed rats. Identification of novel fragments of IAPP, in addition to IAPP(1-37), offers a promise for the elucidation of the physiological function of IAPP and the identification of factors that regulate the biosynthesis and catabolism of the peptide.
Miyazato
M
M
Department of Medicine, Miyazaki Medical College, Japan.
Nakazato
M
M
Shiomi
K
K
Kangawa
K
K
Matsuo
H
H
Matsukura
S
S
D000595:Amino Acid Sequence; D000682:Amyloid / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification*; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004435:Eating; D005215:Fasting; D006801:Humans; D058228:Islet Amyloid Polypeptide; D008297:Male; D008969:Molecular Sequence Data; D010179:Pancreas / Q000737:chemistry*; D010446:Peptide Fragments / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification*; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley
D000682:Amyloid; D058228:Islet Amyloid Polypeptide; D010446:Peptide Fragments