Title : The precursor to B-type natriuretic peptide is an O-linked glycoprotein
Abstract :
Human pro-B-type natriuretic peptide ( proBNP ), the precursor for B-type natriuretic peptide ( BNP ), was expressed in Chinese hamster ovary cells (CHO) and compared by Western blot analysis to BNP cross-reacting material immunoprecipitated from the plasma of heart failure patients
Both recombinant and native forms co-migrated as a diffuse band centered around 25 kDa and were reduced to a 12 kDa species by treatment with a mixture of O-link deglycosylation enzymes
The 108-amino acid CHO-expressed protein was examined by tryptic mapping and LC-MS and found to be an O-linked glycoprotein
Determination of the sites of O-glycosyl addition by blank cycle sequencing of tryptic and Glu-C (Staphylococcus aureus V8 protease ) peptides showed that there are seven sites of glycosylation confined to a 36-amino acid residue stretch within the center of the propeptide region
This data is consistent with previous observations of higher molecular weight isoforms of BNP