title: Pre-cholesterol precursors in gametogenesis.
abstract: Meiosis activating sterols (MAS) are biologically active post-lanosterol intermediates of cholesterol biosynthesis that are synthetized primarily in the gonads, including the sperm. MAS reinitiate the meiosis of oocytes in vitro while in vivo they seem to contribute to the oocyte quality and the progression of meiosis. The mRNAs for the MAS-producing enzyme lanosterol 14alpha-demethylase (CYP51) arise by alternative poly (A) signal selection. Only signals with low cleavage activity are used in the testis. Translation of mammalian CYP51s starts at one of the tandem in-frame ATGs. CYP51 protein of the bull is shorter compared to the human due to the usage of a more downstream translation start site. CYP51 proteins are post-translationally modified by glycosylations in the Golgi and on acrosomal membranes of the sperm. Green fluorescence protein-based ex vivo system has been developed to aid studying the intracellular transport of the MAS-producing CYP51. The influence of the post-translational modifications on MAS-synthesizing capacity is under investigation.
authors.affiliation: Medical Centre for Molecular Biology, Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1000 Ljubljana, Slovenia. damjana.rozman@mf.uni-lj.si
authors.forename: Damjana
authors.initials: D
authors.lastname: Rozman
authors.forename: Matej
authors.initials: M
authors.lastname: Seliskar
authors.forename: Marko
authors.initials: M
authors.lastname: Cotman
authors.forename: Martina
authors.initials: M
authors.lastname: Fink
mesh_terms: D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D018387:Codon, Initiator; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D010442:Peptide Chain Initiation, Translational; D026723:Polyadenylation; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013091:Spermatogenesis / Q000235:genetics / Q000502:physiology*; D058886:Sterol 14-Demethylase; D013261:Sterols / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C548418:CYP51A1 protein, human; D018387:Codon, Initiator; D012333:RNA, Messenger; D013261:Sterols; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol; D010088:Oxidoreductases; C548415:Cyp51 protein, mouse; D058886:Sterol 14-Demethylase