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Differential glycosylation of N‐POMC 1–77 regulates the production of γ 3 ‐MSH by purified pro‐opiomelanocortin converting enzyme A possible mechanism for tissue‐specific processing
Author(s) -
Birch Nigel P.,
Estivariz Fernando E.,
Bennett Hugh P.J.,
Lob Y.Peng
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)81257-9
Subject(s) - glycosylation , enzyme , chemistry , mechanism (biology) , biochemistry , microbiology and biotechnology , biology , physics , quantum mechanics
The amino terminus of bovine pro‐opiomelanocortin (N‐POMC 1–77 ) is partially processed in the intermediate lobe of the pituitary to N‐POMC 1–49 and lys‐γ 3 ‐melanotropin. Two pools of N‐POMC 1–77 were isolated which were differentially glycosylated at threonine 45 , while N‐POMC 1–49 isolated from bovine intermediate lobe extracts existed in a non‐glycosylated form. This suggested that differential O ‐linked glycosylation of N‐POMC 1–77 may regulate cleavage at the Arg 49 ‐Lys 50 processing site. We tested this hypothesis by incubating N‐POMC 1–77 glycoforms with purified pro‐opiomelanocortin converting enzyme. Only non‐ O ‐glycosylated N‐POMC 1–77 and O ‐glycosylated N‐POMC 1–77 with truncated oligosaccharide sidechains were sensitive to cleavage and generated predominantly lys‐γ 3 ‐melanotropin, identified by high‐performance liquid chromatography. These data provide the first functional evidence to support a role for differential O ‐linked glycosylation in the regulation of the processing of the N‐terminus of bovine POMC.