Structural heterogeneity, post-translational modifications, and biological activities of SV-IV, a major protein secreted from the rat seminal vesicle epithelium.
The primary structure of purified SV-IV, a major secretory protein synthesized by the rat seminal vesicle (SV) epithelium, was analysed by electrospray mass spectrometry (ES-MS). The protein was found to be highly heterogeneous. The various components were separated and identified by reversed phase high-performance liquid chromatography (HPLC) on line with ES-MS. Structural characterization of the SV-IV cyanogen bromide digests revealed the occurrence of a Val/Met substitution in about 50% of the purified protein molecules. We suggest that this mutation is the expression of a genetic polymorphism. Other minor components, corresponding to structural changes (fragmentation, deletion, and phosphorylation) of SV-IV and probably due to post-translational modifications of the native protein, were also detected. In particular, by using protein tyrosine phosphatase hydrolysis combined with ES-MS, we demonstrated that, in the phosphorylated species of SV-IV, a single phosphate group was covalently bound to the Tyr-36 residue. The significance of these findings in relation to the regulation of important biological processes, such as immune response, blood coagulation, inflammatory reaction, and mammalian reproduction, are discussed.
Ferranti
P
P
Centro Internazionale di Servizi di Spettrometria di Massa del C.N.R., Napoli, Italy.
Mamone
G
G
Malorni
A
A
Guardiola
J
J
Stiuso
P
P
Metafora
S
S
D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D002853:Chromatography, Liquid; D003488:Cyanogen Bromide; D004563:Electrochemistry; D004848:Epithelium / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D008297:Male; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010455:Peptides / Q000032:analysis / Q000302:isolation & purification; D010766:Phosphorylation; D029584:Prostatic Secretory Proteins; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D029589:Seminal Plasma Proteins; D012669:Seminal Vesicles / Q000737:chemistry* / Q000378:metabolism
D010455:Peptides; D029584:Prostatic Secretory Proteins; D011506:Proteins; D029589:Seminal Plasma Proteins; C043076:beta-microseminoprotein; D011505:Protein-Tyrosine Kinases; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D003488:Cyanogen Bromide