Lotte Bach Larsen1, Peter Ravn1, Anni Boisen1, Lars Berglund1, Torben E. Petersen1
1Protein Chemistry Laboratory, University of Adrhus, Denmark
Tóm tắt
A 20‐kDa glycoprotein, EPV20, was isolated from bovine milk and characterized. The primary structure was determined by cDNA and protein sequencing combined with mass spectrometry. EPV20 is a 130‐residue polypeptide synthesized with a 19‐residue signal peptide. The function of EPV20 is unknown, but it displays 79% sequence similarity to a putative protein deduced from a human testis cDNA sequence designated HE1 (human epididymis clone 1) (Kirchhoff, C., 1992. EMBL/GeneBank/DDBJ Databases, accession number X6769X). Northern blot analysis showed the bovine EPV20 to be expressed in kidney, spleen, liver and mammary gland, but remarkably not in bovine testis. The six Cys residues of EPV20 were found to be disulfide‐linked in a 1–6, 2–3 and 4–5 pattern. This disulfide arrangement has been observed in other proteins, e.g. in human prostatic acid phosphatase, but the spacing between the cystines differs. Therefore, EPV20 represents a new structure among the large group of proteins containing domains with three disulfide bonds.
