Recombinant Arabidopsis thaliana Protein DA1 (DA1), partial

Ubiquitin receptor that limits final seed and organ size by restricting the period of cell proliferation. May act maternally to control seed mass. Acts synergistically with DA2 to regulate seed size. Functions synergistically with DA2 to restrict cell proliferation in the maternal integuments of ovules and developing seeds. Functions antagonistically in a common pathway with UBP15 to regulate seed size. Associates physically with UBP15 and modulates the stability of UBP15, which promote cell proliferation in the integuments of ovules and developing seeds. Functions as peptidase and cleaves the N-terminal sequence of E3 ubiquitin-protein ligases BB and DA2 in a ubiquitin-dependent manner. Cleaves the deubiquitinating enzyme UBP15, which promotes cell proliferation, and the transcription factors TCP15 and TCP22, which promote cell proliferation and repress endoreduplication. Involved in the promotion of leaf senescence, in addition to its function in restricting plant growth. Acts redundantly with DAR1 and DAR2 to regulate endoreduplication during leaf development. Together with DAR1 and DAR2, modulates the protein stability of the transcription factors TCP14 and TCP15, which repress endoreduplication by directly regulating the expression of cell-cycle genes.