Parathyroid hormone-related protein. Evidence for secretion of a novel mid-region fragment by three different cell types.

摘要: The cDNA-predicted amino acid sequence of parathyroid hormone-related protein (PTHrP) contains multiple basic motifs, suggesting that PTHrP undergoes extensive post-translational processing prior to secretion. secretory forms the peptide are currently unknown. To identify these forms, medium was harvested from three cell types: human renal carcinoma (SKRC-1) cells, keratinocytes, and rat insulinoma cells stably transfected with cDNA for PTHrP(1-141) (RIN-141 cells). Amino-terminal species were immunopurified using an anti-PTHrP(1-36) column, mid-region anti-PTHrP(37-74) column. peptides in extracts further resolved by reverse phase high performance liquid chromatography (RP-HPLC) identified region-specific immunoassays. SKRC-1 RIN-141 secreted distinct amino-terminal a novel, non-amino-terminal, fragment. Sequence sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated fragment begins at 38 is approximately 70 acids length. Comparison RP-HPLC elution patterns suggests keratinocytes secrete similar or identical Immunofluorescence studies revealed Golgi pattern granule These indicate 1) secreted, including novel fragment; 2) Arg37 serves as cleavage site least types; 3) PTHrP(1-36) likely be authentic form PTHrP; 4) appears packaged into granules. marked interspecies conservation this it will have important biological functions.