Abstract
It has been shown previously that neonatal and fetal rat islets in culture secrete IGF I as measured by specific radioimmunoassay. We hereby report the partial purification and biochemical characterization of IGF I produced and secreted by fetal rat islets in culture. Fetal islets were incubated in RPMI 1640 with 1% fetal calf serum with or without (3H) leucine and (35S) methionine. The conditioned media were acidified to pH 2.7 and chromatographed on Biogel P 100 in acid to separate IGF I from its binding proteins. The quantity of immunoreactive IGF I present in the media increased with time and plateaud after 48 hours in culture reaching a value of 1 ng IGF I for 300 islets. Part of the total radioactivity (3%) comigrated on Biogel P100 with immunoreactive IGF I. This fraction was further purified by HPLC on a microbondapak C18 column and eluted with a linear gradient of acetonitrile. Material which comigrated with pure IGF I (39% acetonitrile) was then purified by chromatofocalisation on PBE 96 column. Part of the radioactivity (30%) eluted at the same basic pH (8.55) than IGF I produced by other fetal rat cells in culture and was immunoprecipitable by anti-IGFI Ab.
In conclusion: labelled material was produced and secreted in vitro by islet cells with identical Mol Weight, hydrophobicity and isoelectric point than native IGF I.
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Scharfmann, R., Czernichow, P. 33 PRODUCTION OF LABELLED IGF I BY ISLETS CELLS IN CULTURE: BIOCHEMICAL CHARACTERIZATION. Pediatr Res 24, 522 (1988). https://doi.org/10.1203/00006450-198810000-00054
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DOI: https://doi.org/10.1203/00006450-198810000-00054