title: Gene sharing by delta-crystallin and argininosuccinate lyase.
abstract: The lens structural protein delta-crystallin and the metabolic enzyme argininosuccinate lyase (ASL; L-argininosuccinate arginine-lyase, EC 4.3.2.1) have striking sequence similarity. We have demonstrated that duck delta-crystallin has enormously high ASL activity, while chicken delta-crystallin has lower but significant activity. The lenses of these birds had much greater ASL activity than other tissues, suggesting that ASL is being expressed at unusually high levels as a structural component. In Southern blots of human genomic DNA, chicken delta 1-crystallin cDNA hybridized only to the human ASL gene; moreover, the two chicken delta-crystallin genes accounted for all the sequences in the chicken genome able to cross-hybridize with a human ASL cDNA, with preferential hybridization to the delta 2 gene. Correlations of enzymatic activity and recent data on mRNA levels in the chicken lens suggest that ASL activity depends on expression of the delta 2-crystallin gene. The data indicate that the same gene, at least in ducks, encodes two different functions, an enzyme (ASL) and a structural protein (delta-crystallin), although in chickens specialization and separation of functions may have occurred.
authors: Laboratory of Molecular and Developmental Biology, National Eye Institute, Bethesda, MD 20892.
authors: J
authors: J
authors: Piatigorsky
authors: W E
authors: WE
authors: O'Brien
authors: B L
authors: BL
authors: Norman
authors: K
authors: K
authors: Kalumuck
authors: G J
authors: GJ
authors: Wistow
authors: T
authors: T
authors: Borras
authors: J M
authors: JM
authors: Nickerson
authors: E F
authors: EF
authors: Wawrousek
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001123:Argininosuccinate Lyase / Q000235:genetics*; D001483:Base Sequence; D002642:Chick Embryo; D003459:Crystallins / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004372:Ducks; D004625:Embryo, Nonmammalian; D005796:Genes; D006801:Humans; D008190:Lyases / Q000235:genetics*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D003459:Crystallins; D004247:DNA; D008190:Lyases; D001123:Argininosuccinate Lyase