Recombinant Arabidopsis thaliana 26S proteasome regulatory subunit 4 homolog A (RPT2A)

The 26S protease is involved in the ATP-dependent degradation of ubiquitinated proteins. The regulatory (or ATPase) complex confers ATP dependency and substrate specificity to the 26S complex (Probable). Interacts with transit peptides of proteins targeted to the chloroplast, and may be involved in the degradation of unimported plastid protein precursors. Is required for the maintenance of postembryonic root and shoot meristems. Has a specific role in the regulation of organs size. Acts redundantly with RPT2B in the regulation of gametogenesis. With RPT2B plays a critical role in 26S proteasome assembly. Acts as an upstream signaling component for inducing both defense and morphological phenotypes in the constitutive active uni-1D mutant. Acts as negative regulator of endoreduplication in trichome cells. May function after the completion of the third endoreduplication step (8C to 16C) mediated by RHL1. Acts as negative regulator of transcriptional gene silencing (TGS) at specific endogenous genes through DNA methylation. Promotes post-transcriptional gene silencing (PTGS) by limiting the degradation of transgene aberrant RNAs by the RNA quality control (RQC) machinery, thus favoring their entry into cytoplasmic siRNA bodies where they can trigger PTGS. Involved in tolerance to zinc deficiency, possibly through alleviation of oxidative stresses or processing of poly-ubiquitinated proteins. Required for resistance to the fungal pathogen Golovinomyces cichoracearum.