Concanavalin A variants of the fetoacinar pancreatic protein in the developing human pancreas and other biological sources

Abstract

Two new sources for the fetoacinar pancreatic protein (FAP protein) are described in this study: amniotic fluids taken at 18 weeks gestation, and pancreatic juices from patients with pancreatic pathology. The FAP protein from different biological sources showed two kinds of molecular heterogeneity; (a) molecular weight, and (b) lectin-binding affinity. By Western blot the protein was shown to exist either as a doublet (the high- M r component at kDa and the second in the range 80–100 kDa) or a single band (100 kDa) depending on the source. By chromatography on Con A-Sepharose the protein could be separated into two variants, reactive and nonreactive. Most of the protein was present as the Con A-nonreactive variant. The Western-blot patterns of both variants in a given sample were identical. The FAP protein expression had an oncodevelopmental character; maximal concentration was seen in middle-gestation fetal pancreas extracts. Expression of the FAP protein Con A variants followed the same developmental pattern as that of total FAP protein, and their relative amounts remained almost constant during fetal growth. Evidence is given for the presence of lectin and molecular-weight heterogeneities of the protein as well as for the lack of a developmental pattern for the expression of these variants.