title: Haprin, a novel haploid germ cell-specific RING finger protein involved in the acrosome reaction.
abstract: The acrosome reaction (i.e. the exocytosis of the sperm vesicle) is a prerequisite for fertilization, but its molecular mechanism is largely unknown. We have identified a cDNA clone for a gene named haprin, which encodes a haploid germ cell-specific RING finger protein. This protein is a novel member of the RBCC (RING finger, B-box type zinc finger, and coiled-coil domain) motif family that has roles in several cellular processes, such as exocytosis. It is transcribed exclusively in testicular germ cells after meiotic division. Western blot and immunohistochemical analyses showed the molecular weight of Haprin protein to be Mr approximately 82,000. It was localized in the acrosomal region of elongated spermatids and mature sperm and was not present in acrosome-reacted sperm. The specific antibody against the RING finger domain of Haprin inhibited the acrosome reaction in permeabilized sperm. These results indicated that the novel RBCC protein Haprin plays a key role in the acrosome reaction and fertilization.
authors.affiliation: Department of Science for Laboratory Animal Experimentation, Research Institute for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Kouichi
authors.initials: K
authors.lastname: Kitamura
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Nishimune
mesh_terms: D000177:Acrosome / Q000737:chemistry; D020101:Acrosome Reaction / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D005306:Fertilization; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D015723:Gene Library; D007150:Immunohistochemistry; D008297:Male; D008540:Meiosis; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012333:RNA, Messenger / Q000032:analysis; D029589:Seminal Plasma Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017422:Sequence Analysis, DNA; D013087:Spermatids / Q000737:chemistry / Q000648:ultrastructure; D013094:Spermatozoa / Q000737:chemistry / Q000648:ultrastructure; D013737:Testis / Q000737:chemistry; D044767:Ubiquitin-Protein Ligases; D000070584:Tripartite Motif Proteins
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D029589:Seminal Plasma Proteins; C480040:Trim36 protein, mouse; D044767:Ubiquitin-Protein Ligases; D000070584:Tripartite Motif Proteins