Identification of voltage-dependent Ca2+ channels in sea urchin sperm.
Functional evidence indicates that voltage-dependent Ca2+ (Cav) channels participate in sea urchin sperm motility and the acrosome reaction (AR), however, their molecular identity remains unknown. We have identified transcripts for two Ca2+ channel alpha1 subunits in sea urchin testis similar in sequence to Cav1.2 and Cav2.3. Antibodies against rat Cav1.2 and Cav2.3 channels differentially label proteins in the flagella and acrosome of mature sea urchin sperm. The Cav channel antagonists nifedipine and nimodipine, which inhibit the AR, diminish the intracellular Ca2+ elevation induced by a K+-induced depolarization in valinomycin-treated sperm. These findings reveal that Cav1.2 and Cav2.3 channels could participate in motility and/or the AR in sea urchin sperm.
Granados-Gonzalez
G
G
Department of Developmental Genetics and Molecular Physiology, Institute of Biotechnology, UNAM, Avenida Universidad 2001, Col. Chamilpa, CP 62210, Cuernavaca, Mor., Mexico.
Mendoza-Lujambio
I
I
Rodriguez
E
E
Galindo
B E
BE
Beltrán
C
C
Darszon
A
A
D000177:Acrosome / Q000737:chemistry; D020101:Acrosome Reaction; D000595:Amino Acid Sequence; D000818:Animals; D015220:Calcium Channels / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D002465:Cell Movement; D005407:Flagella / Q000737:chemistry; D008297:Male; D010802:Phylogeny; D012333:RNA, Messenger / Q000032:analysis; D012617:Sea Urchins / Q000737:chemistry* / Q000166:cytology; D013094:Spermatozoa / Q000737:chemistry*
D015220:Calcium Channels; D012333:RNA, Messenger