title: Identification of a fertility-associated protein in bull seminal plasma as lipocalin-type prostaglandin D synthase.
abstract: The objective of this study was to characterize a 26-kDa seminal plasma protein previously shown to be prevalent in bulls of high fertility. Spots of this protein, excised and electroeluted from two-dimensional SDS-PAGE gels, were used for N-terminal amino acid sequencing and for preparation of antiserum in rabbits. The N-terminal amino acid sequence (ALQPNFEEDKFLGRWFTSGL) was 75% identical and 100% homologous to lipocalin-type prostaglandin (PG) D synthase isolated from human cerebrospinal fluid (CSF). Western blots of purified 26-kDa protein cross-reacted with polyclonal antibodies against lipocalin-type PGD synthase isolated from rat brain and human CSF. Immunoreactive bands at 26 kDa appeared in Western blots of seminal plasma and cauda epididymal fluid (CEF). A 29-kDa band appeared in blots of rete testis fluid (RTF). PGD synthase activity was detected in seminal plasma, CEF, and RTF. The cDNA for bovine lipocalin-type PGD synthase, isolated by reverse transcription-polymerase chain reaction, contained a coding region of 573 base pairs corresponding to 191 amino acids. The amino acid sequence was 63-80% identical to that of the enzyme of other mammals. These results establish that the 26-kDa fertility-associated protein in bull seminal plasma is lipocalin-type PGD synthase. Although we do not yet know the role of lipocalin-type PGD synthase in the male genital tract, we speculate that this protein may play an important role in both the development and the maturation of sperm.
authors.affiliation: Department of Dairy and Animal Science, Pennsylvania State University, University Park 16802, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Gerena
authors.forename: D
authors.initials: D
authors.lastname: Irikura
authors.forename: Y
authors.initials: Y
authors.lastname: Urade
authors.forename: N
authors.initials: N
authors.lastname: Eguchi
authors.forename: D A
authors.initials: DA
authors.lastname: Chapman
authors.forename: G J
authors.initials: GJ
authors.lastname: Killian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005298:Fertility / Q000502:physiology*; D006801:Humans; D007120:Immunochemistry; D019746:Intramolecular Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054834:Lipocalins; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011817:Rabbits; D051381:Rats; D012661:Semen / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D054834:Lipocalins; D019746:Intramolecular Oxidoreductases; C022466:prostaglandin R2 D-isomerase