RNA 3'-terminal phosphate cyclase (RTCA)

Catalyzes the conversion of 3'-phosphate to a 2',3'- cyclic phosphodiester at the end of RNA. The mechanism of action of this enzyme occurs in 3 steps: (A) adenylation of this enzyme by ATP; (B) transfer of adenylate to an RNA-N3'P to produce RNA- N3'PP5'A; (C) and assault of the adjacent 2'-hydroxyl on the 3'- phosphorus at the diester linkage to generate the cyclic end product.

The biological role of this enzyme is unknown but it is very likely to function in some aspects of cellular RNA processing. .