Delineation of the functional domains of the extracellular region of YWK-II Protein/APLP2 of sperm membrane.
The sperm membrane protein, designated as YWK-II protein/APLP2, is a member of the amyloid precursor protein (APP) superfamily and is a type I transmembrane protein involved in fertilization. Here, the structure-function of the domains of YWK-II protein was examined. Five segments with overlapping ends encompassing the entire extracellular region of mouse YWK-II gene were prepared, cloned and separately expressed in E. coli. The recombinant YWK-II segments were fused with glutathione S-transferase (GST), purified and evaluated for their antifertility activities by measuring their capacity to block in vitro mouse sperm-egg interaction. The structural domain(s) involved in the fertilization process was identified. The polypeptide segment corresponding to position 22-207 of YWK-II-763 inhibited the early stage of fertilization when the spermatozoa interacted with zona-free eggs; whereas the polypeptide segment 201-395 (lacking 309-364) of YWK-II-763 blocked sperm-egg membrane fusion. The remaining three segments, 201-395, 389-574 and 517-704 (lacking 613-624) of YWK-II-763, did not influence the in vitro fertilization process. The present results suggest that segment 22-308 of YWK-II-763 participates in the binding and fusion of sperm and egg plasma membranes thereby promoting fertilization.
Zhuang
Dazhong
D
National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, 5 Dong Dan San, Tiao, Beijing, 100005, China.
Wang
Yong
Y
Yang
Chunbo
C
Qiao
Yuan
Y
Miao
Shiying
S
Koide
Samuel S
SS
Wang
Linfang
L
D000595:Amino Acid Sequence; D016564:Amyloid beta-Protein Precursor / Q000235:genetics* / Q000502:physiology*; D000818:Animals; D002462:Cell Membrane; D004926:Escherichia coli; D005260:Female; D005982:Glutathione Transferase / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes; D011480:Protease Inhibitors; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000737:chemistry / Q000502:physiology*; D013329:Structure-Activity Relationship
D016564:Amyloid beta-Protein Precursor; C492952:Aplp2 protein, mouse; D008565:Membrane Proteins; D011480:Protease Inhibitors; D005982:Glutathione Transferase