The protein complexity of the cytoskeleton of bovine and human sperm heads: the identification and characterization of cylicin II.
The cytoskeletal calyx of mammalian sperm heads surrounding the basolateral part of the nucleus contains two kinds of basic proteins: Calicin, a polypeptide of approximate M(r) 60,000 as estimated from SDS-PAGE, and the group of the very basic cylicins (pI > 10.0), formerly designated as "multiple-band polypeptides." Recently, bovine cylicin I has been cDNA cloned and identified as a new type of a cytoskeletal protein, which contains numerous Lys-Lys-Asp tripeptides accumulated in nine central repetitive units predicted to form alpha-helices. We now report the cDNA cloning and localization of a second species of cylicin, bovine cylicin II, present in bovine and human sperm heads: Cylicin II (488 amino acids, M(r) 53,561, pI 10.55) shows the same prominent molecular characteristics as cylicin I, including a high content of charged amino acids, the abundance of Lys-Lys-Asp tripeptides, and repetitive units of presumably alpha-helical configuration, but also presents some differences. As with cylicin I mRNA, the 2.6-kb mRNA has also been shown to be specifically expressed in testis. The possible existence of a larger cylicin multigene family and its contribution to the cytoskeleton and the morphogenesis of the sperm head are discussed.
Hess
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Division for Cell Biology, German Cancer Research Center, Heidelberg.
Heid
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Zimbelmann
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Franke
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry*; D018076:DNA, Complementary; D015723:Gene Library; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013077:Sperm Head / Q000737:chemistry / Q000378:metabolism*
C093368:CYLC2 protein, Bos taurus; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; C093367:cylicin protein, Bos taurus