cDNA cloning reveals the molecular structure of a sperm surface protein, PH-20, involved in sperm-egg adhesion and the wide distribution of its gene among mammals.

Abstract

Abstract. Sperm binding to the egg zona pellucida in mammals is a cell-cell adhesion process that is generally species specific. The guinea pig sperm protein PH-20 has a required function in sperm adhesion to the zona pellucida of guinea pig eggs. PH-20 is located on both the sperm plasma membrane and acrosomal membrane. We report here the isolation and sequence of a full-length eDNA for PH-20 (available from EMBL/GenBank/DDBJ under accession number X56332). The derived amino acid sequence shows a mature protein of 468 amino acids containing six N-linked glycosylation sites and twelve cysteines, eight of which are tightly clustered near the COOH terminus. The sequence indicates PH-20 is a novel protein with no relationship to the mouse sperm adhesion protein galactosyl transferase and no significant homology with other known proteins. The two PH-20 populations, plasma membrane and acrosomal membrane, could arise because one form of PH-20 is encoded and differentially targeted at different spermatogenic stages. Alternatively, two different forms of PH-20 could be encoded. Our evidence thus far reveals only one sequence coding for PH-20: Southern blots of guinea pig genomic DNA indicated there is a single PH-20 gene, Northern blots showed a single size PH-20 message (~2.2 kb), and no sequence variants were found among the sequenced eDNA clones. Crossspecies Southern blots reveal the presence of a homologue of the PH-20 gene in mouse, rat, hamster, rabbit, bovine, monkey, and human genomic DNA, showing the PH-20 gene is conserved among mammals.

Hyaluronidases - a group of neglected enzymes

“…This protein is present on the posterior head and the acrosomal membrane of mammalian sperm. Via cDNA cloning, the amino acid sequence of the guinea pig protein could be elucidated (Lathrop et al, 1990). PH-20 is originally synthesized as a polypeptide with an apparent molecular weight of 64 kDa, and it is bound to the membrane via a glycosyl-phosphatidyl-inositol (GPI) anchor.…”

“…A comparison of the sequence of bee and hornet venom hyases Lu et al, 1995) with those of human, monkey, mouse, and guinea pig PH-20 protein (Lathrop et al, 1990;Y. Lin et al, 1993Y.…”

Assessment of contraceptive vaccines based on recombinant mouse sperm protein PH20

“…It is expressed in both the testis and epididymis and is present in sperm and in the luminal fluid of the epididymis (Deng et al 1999, Zhang & Martin-DeLeon 2003a. The PH20 protein is widely conserved among mammals, and homologues have been cloned from many species including guinea pig, where the protein was first identified (Lathrop et al 1990), rat (Hou et al 1996), rabbit , fox (ten Have et al 1998), pig (Day et al 2002), monkey and man (Lin et al 1993).…”

Bee venom hyaluronidase is homologous to a membrane protein of mammalian sperm.

“…The deduced amino acid sequence ofbee venom hyaluronidase shows no discernible similarity to the hyaluronidase from bacteriophage H4489A of S. pyogenes (2). A search in the EMBL data bank (13) revealed that bee venom hyaluronidase is related to PH-20, a protein located on the plasma membrane and the acrosomal membrane ofguinea pig sperm (6). The two polypeptides share 36% identity in a region encompassing amino acids 14-303 of the bee enzyme and 17-307 of PH-20 (Fig.…”

“…As described in this paper, by using this information we were able to isolate two clones that encode the hyaluronidase precursor from a cDNA library prepared from bee venom glands. The sequence ofthis insect enzyme* shows homology to a protein present in guinea pig sperm (6).…”