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Spermatozoa contain a guanine nucleotide-binding protein ADP-ribosylated by pertussis toxin

J K Bentley, D L Garbers, S E Domino

    Biochemical and Biophysical Research Communications
    |July 31, 1986
    PubMed

    Insights

    Spermatozoa across species contain a protein modified by pertussis toxin, indicating a novel guanine nucleotide-binding protein involved in sperm function. This discovery reveals a conserved signaling mechanism in diverse sperm types.

    Area of Science:

    • Cell Biology
    • Reproductive Biology
    • Biochemistry

    Background:

    • Spermatozoa utilize complex signaling pathways for fertilization.
    • Guanine nucleotide-binding proteins (G-proteins) are crucial regulators of cellular processes.

    Purpose of the Study:

    • To identify and characterize guanine nucleotide-binding proteins in spermatozoa.
    • To investigate the presence and function of pertussis toxin substrates in sperm.

    Main Methods:

    • ADP-ribosylation assays using pertussis toxin and cholera toxin.
    • Copurification with [gamma-35S]GTP binding activity.
    • Peptide mapping (chymotryptic digestion) and Western blot analysis using specific antisera.

    Main Results:

    • A membrane-bound protein, ADP-ribosylated by pertussis toxin, was identified in invertebrate and vertebrate spermatozoa.
    • The molecular mass of this protein varied (39-41 kDa) across species.
    • The protein from sea urchin sperm showed similarities to the alpha-subunit of Go from rat brain and copurified with GTP-binding activity.
    • Antibodies against the beta-subunit of transducin recognized a sperm protein.

    Conclusions:

    • Spermatozoa possess a conserved guanine nucleotide-binding coupling protein.
    • This protein is a substrate for pertussis toxin, suggesting its involvement in G-protein-mediated signaling pathways in sperm.
    • These findings represent the first description of such a protein in sperm.

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