Purification and characterization of prosomatostatin from rat brain.
A high molecular weight somatostatin-immunoreactive polypeptide, presumably prosomatostatin, was purified from rat brain and characterized. Purification steps included extraction with 2 M acetic acid, precipitation of contaminating proteins at pH 6.5, Sephadex G-50 chromatography, immunoaffinity chromatography, and HPLC steps (size exclusion and reversed-phase HPLC). The protein was purified more than 30,000-fold. It is heat stable. Sodium dodecyl sulfate-gel electrophoresis and immunoblotting revealed one major immunoreactive band of approximately 13,000 molecular weight which roughly corresponds to the size of prosomatostatin as derived from its DNA sequence. Isoelectric focusing and two-dimensional sodium dodecyl sulfate-gel electrophoresis gave a single immunoreactive spot at a pI of 5.4. The polypeptide did not bind to concanavalin A or to wheat germ lectin columns, suggesting lack of N-glycosylation in the molecule. Regional distribution of prosomatostatin varied between 6%, 10%, and 18% of total immunoreactivity in the brainstem, cortical areas, and striatum, respectively.
Strieder
G
G
Department of Pharmacology, University of Innsbruck, Austria.
Sperk
G
G
D000818:Animals; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004586:Electrophoresis / Q000379:methods; D008297:Male; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification; D011498:Protein Precursors / Q000302:isolation & purification*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000302:isolation & purification*; D014018:Tissue Distribution
D010455:Peptides; D011498:Protein Precursors; C029993:somatostatin-like peptides; D013004:Somatostatin; C028456:prosomatostatin