Does fish represent an intermediate stage in the evolution of ureotelic cytosolic arginase I?

作者：Srivastava Shilpee^*; Ratha B K

来源：Biochemical and Biophysical Research Communications, 2010, 391(1): 1-5.

DOI：10.1016/j.bbrc.2009.11.018

• Arginase
• Ornithine-urea cycle
• Heteropneustes fossilis
• Ureogenic
• Evolution
• Isoenzymes

Aiginase catalyses the last step of the urea cycle At least two isoenzymes of arginase are known, cytosolic ARG I and mitochondrial ARG II ARG I is predominantly expressed in liver cytosol, as a part of urea cycle in ureotelic animals The second isoform ARG II is primarily responsible for non-ureogenic functions, expressed in mitochondria of both hepatic and non-hepatic tissues in most vertebrates Most micro-organisms and invertebrates are known to have only one type of arginase. whose function is unrelated to ornithine-urea cycle (OUC) However. in ureo-osmotic marine elasmobranchs aiginase is localized in liver mitochondria as a part of OUC to synthesize Urea for osmoregulation An evolutionary transition occurred in arginase enzyme in terrestrial ureotelic vertebrates, with the evolution of ARG I from a pre-existing ancestral mitochondrial ARG II. This cytosolic ARG I activity is supposed to have first appeared in lung fishes, but

• 出版日期2010-1-1