title: Adenylate kinases 1 and 2 are part of the accessory structures in the mouse sperm flagellum.
abstract: Proper sperm function depends on adequate ATP levels. In the mammalian flagellum, ATP is generated in the midpiece by oxidative respiration and in the principal piece by glycolysis. In locations where ATP is rapidly utilized or produced, adenylate kinases (AKs) maintain a constant adenylate energy charge by interconverting stoichiometric amounts of ATP and AMP with two ADP molecules. We previously identified adenylate kinase 1 and 2 (AK1 and AK2) by mass spectrometry as part of a mouse SDS-insoluble flagellar preparation containing the accessory structures (fibrous sheath, outer dense fibers, and mitochondrial sheath). A germ cell-specific cDNA encoding AK1 was characterized and found to contain a truncated 3' UTR and a different 5' UTR compared to the somatic Ak1 mRNA; however, it encoded an identical protein. Ak1 mRNA was upregulated during late spermiogenesis, a time when the flagellum is being assembled. AK1 was first seen in condensing spermatids and was associated with the outer microtubular doublets and outer dense fibers of sperm. This localization would allow the interconversion of ATP and ADP between the fibrous sheath where ATP is produced by glycolysis and the axonemal dynein ATPases where ATP is consumed. Ak2 mRNA was expressed at relatively low levels throughout spermatogenesis, and the protein was localized to the mitochondrial sheath in the sperm midpiece. AK1 and AK2 in the flagellar accessory structures provide a mechanism to buffer the adenylate energy charge for sperm motility.
authors.affiliation: Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Wenlei
authors.initials: W
authors.lastname: Cao
authors.forename: Lisa
authors.initials: L
authors.lastname: Haig-Ladewig
authors.forename: George L
authors.initials: GL
authors.lastname: Gerton
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Moss
mesh_terms: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D000263:Adenylate Kinase / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity; D013081:Sperm Motility; D013082:Sperm Tail / Q000201:enzymology*; D013091:Spermatogenesis / Q000235:genetics / Q000502:physiology*; D013737:Testis / Q000201:enzymology
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D007527:Isoenzymes; D000263:Adenylate Kinase; C110939:adenylate kinase 1; C110938:adenylate kinase 2