2j9i

Publication Abstract from PubMed

Lengsin is a major protein of the vertebrate eye lens. It belongs to the hitherto purely prokaryotic GS I branch of the glutamine synthetase (GS) superfamily, but has no enzyme activity. Like the taxon-specific crystallins, Lengsin is the result of the recruitment of an ancient enzyme to a noncatalytic role in the vertebrate lens. Cryo-EM and modeling studies of Lengsin show a dodecamer structure with important similarities and differences with prokaryotic GS I structures. GS homology regions of Lengsin are well conserved, but the N-terminal domain shows evidence of dynamic evolutionary changes. Compared with birds and fish, most mammals have an additional exon corresponding to part of the N-terminal domain; however, in human, this is a nonfunctional pseudoexon. Genes related to Lengsin are also present in the sea urchin, suggesting that this branch of the GS I family, supplanted by GS II enzymes in vertebrates, has an ancient role in metazoans.

Lengsin is a survivor of an ancient family of class I glutamine synthetases re-engineered by evolution for a role in the vertebrate lens.,Wyatt K, White HE, Wang L, Bateman OA, Slingsby C, Orlova EV, Wistow G Structure. 2006 Dec;14(12):1823-34. PMID:17161372^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.