Authors: Richard Man Kit Yu Minnie Man Lai Wong Ralph Wilson Jack Richard Yuen Chong Kong
Publish Date: 2005/07/15
Volume: 222, Issue: 5, Pages: 757-768
Abstract
Protein phosphatase 2A PP2A is one of the major serine/threonine protein phosphatases in the cell and plays a variety of regulatory roles in metabolism and signal transduction Previously we described the structure and expression of two genes encoding PP2A catalytic subunits PP2Ac—OsPP2A1 and OsPP2A3—in the rice plant Yu et al 2003 Here we report the isolation and characterisation of a second structurally distinguishable PP2Ac subfamily comprised of three additional isogenes OsPP2A2 OsPP2A4 each containing ten introns and OsPP2A5 which contains nine introns Northern blot analysis demonstrated that the three isogenes are ubiquitously expressed in all rice tissues during plant development and differentially expressed in response to high salinity and the combined stresses of drought and heat Phylogenetic analyses indicated that the two PP2Ac subfamilies are descended from two ancient lineages which derived from gene duplications that occurred after the monocotyledon–dicotyledon split In the second subfamily it is proposed that two duplication events were involved in which the initial duplication of a tenintron primordial gene yielded OsPP2A2 and the progenitor of OsPP2A4 and OsPP2A5 The OsPP2A4/OsPP2A5 progenitor in turn underwent a second duplication event resulting in the present day OsPP2A4 and OsPP2A5 It is proposed that loss of the 5′most intron from OsPP2A5 occurred after these two duplication events
Keywords: