The Molecular Biology of Lithostathine (Pancreatic Stone Protein)
Pancreatic secretion of mammals contains about 20 principal protein species (Rinderknecht 1986). Most of these secretory proteins are directly implicated in the digestive process. Our laboratory has reported the presence in human pancreas of a protein apparently devoid of enzyme activity (Montalto et al. 1986) and named secretory pancreatic stone protein (PSP-S) because of its immunological identity with the pancreatic stone protein, the major component of the protein matrix present in calculi of patients suffering from chronic calcifying pancreatitis (CCP). In human pancreatic juice collected over an appropriate mixture of protease inhibitors, PSP-S comprised four species with apparent M r between 16 and 20 kDa, named PSP-S2 to PSP-S5 (de Caro et al. 1988). However, immunoprecipitation of in vitro translation products of pancreatic RNAs showed that PSP-S was synthesised as a single polypeptide (Giorgi et al. 1985a). Hence, PSP-S is a protein entity with a molecular weight heterogeneity probably due to postranslational processing. An additional PSP- S form (PSP-S1) appears in pancreatic juice upon activation. PSP-S1 with a M r of 15 kDa derives from PSP-S2-5 by trypsin-like cleavage of an Arg-Ile bond in the NH2-terminal part of the protein (Rouimi et al. 1987).
KeywordsPancreatic Juice mRNA Concentration Pancreatic Stone Protein Chronic Calcify Pancreatitis Human Pancreatic Juice
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