Isolation of partial cDNAs for rat liver and muscle glycogen phosphorylase isozymes

FEBS Letters

Johnson, Gary L.¹  Chiu, Robert H.²  McDonough, Alicia²  Osawa, Shoji¹  Miller, Thomas B.¹ 

[1] Department of Biochemistry, University of Massachusetts Medical Center, 55 Lake Avenue North, Worcester, MA 01605 U.K.;Department of Physiology and Biophysics, University of Southern California School of Medicine, 1333 San Pablo Street, Los Angeles, CA 90033, USA

关键词: Phosphorylase;    Isozyme;    cDNA;    (Rat;    Liver;    Muscle);   

DOI  :  10.1016/0014-5793(86)80702-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

cDNA clones for the rat liver and muscle glycogen phosphorylase isozymes have been isolated using isozyme-selective antibodies and libraries prepared in the expression vector, λgt11. A 1.2 kb cDNA coding for the carboxy-terminal domain of rat liver phosphorylase was found to have 82% homology with the amino acid sequence of rabbit muscle phosphorylase. Limited sequencing of rat muscle phosphorylase cDNA indicated a 95% homology with the rabbit muscle enzyme. The rat liver clone has eight additional amino acid residues at the COOH-terminus compared to the rat muscle clone. Furthermore, 17 of 26 (65%) residues between amino acids 815–840 differ between liver and muscle isozymes. The similarity in enzymatic properties and conservation of structure except at the COOH-terminus suggest that the liver and muscle phosphorylase isozymes do not exist in order to have significant differences in the regulation of glycogen breakdown in the two tissues. Rather, the phosphorylase isozymes probably evolved for tissue-specific transcriptional regulation of the genes in liver and muscle.

【 授权许可】

Unknown