Arabidopsis thaliana RNA polymerase II subunits related to yeast and humanRPB5

Arabidopsis thaliana contains at least four genes that are predicted to enc ode polypeptides related to the RPB5 subunit found in yeast and human RNA p olymerase II. This subunit has been shown to be the largest subunit common to yeast RNA polymerases I, II, and III (RPABC27). More than one of these g enes is expressed in Arabidopsis suspension culture cells, but only one of the encoded polypeptides is found in purified RNA polymerases II and III. T his polypeptide has a predicted pi of 9.6, matches 14 of 16 amino acids in the amino terminus of cauliflower RPB5 that was microsequenced, and shows 4 2 and 53% amino acid sequence identity with the yeast and human RPB5 subuni ts, respectively. (C) 1999 Elsevier Science B.V. All rights reserved.