Association of Catsper1 or -2 with Ca(v)3.3 leads to suppression of T-type calcium channel activity.
Sperm-specific CatSper1 and CatSper2 proteins are critical to sperm-hyperactivated motility and male fertility. Although architecturally resembling voltage-gated ion channels, neither CatSper1 nor CatSper2 alone forms functional ion channels in heterologous expression systems, which may be related to the absence of yet unidentified accessory subunits. Here we isolated CatSper1- and CatSper2-associated protein(s) from human sperm and analyzed their identities by a multidimensional protein identification technology approach. We identified the T-type voltage-gated calcium channel Ca(v)3.3 as binding to both CatSper1 and CatSper2. The specificity of their interactions was verified by co-immunoprecipitation in transfected mammalian cells. Electrophysiological studies revealed that the co-expression of CatSper1 or CatSper2 specifically inhibited the amplitude of Ca(v)3.3-evoked T-type calcium current without altering other biophysical properties of Ca(v)3.3. Immunostaining studies revealed co-localization of CatSper1 and Ca(v)3.3 on the principal piece of human sperm tail. Furthermore, fluorescence resonance energy transfer analysis revealed close proximity and physical association of these two proteins on the sperm tail. These studies demonstrate that CatSper1 and CatSper2 can associate with and modulate the function of the Ca(v)3.3 channel, which might be important in the regulation of sperm function.
Zhang
Di
D
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064. Electronic address: di.zhang@abbott.com.
Chen
Jun
J
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
Saraf
Anita
A
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
Cassar
Steven
S
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
Han
Ping
P
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
Rogers
John C
JC
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
Brioni
Jorge D
JD
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
Sullivan
James P
JP
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
Gopalakrishnan
Murali
M
Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064.
D015220:Calcium Channels / Q000378:metabolism / Q000502:physiology*; D020747:Calcium Channels, T-Type / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D004594:Electrophysiology; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D007473:Ion Channels / Q000378:metabolism / Q000502:physiology*; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D029589:Seminal Plasma Proteins; D013082:Sperm Tail / Q000737:chemistry; D014162:Transfection
C469757:CACNA1I protein, human; C438823:CATSPER1 protein, human; C482695:CATSPER2 protein, human; D015220:Calcium Channels; D020747:Calcium Channels, T-Type; D007473:Ion Channels; D026901:Membrane Transport Proteins; D029589:Seminal Plasma Proteins