[Novel complexes of gene expression and their role in the appearance and evolution of the genus Homo]

Using genetic (yeast two-hybrid system) and biochemical (co-precipitation of proteins from cellular lysates) approaches, we have performed a whole-genome wide search for interacting partners of the previously described by us variants of hRPB11 subunit of human RNA polymerase II - hRPB1 1balpha, hRPB11calpha and hRPB1 1bbeta, hRPB 11cbeta - in fetal brain and Jurkat cell line libraries. In consequence, the main spectrum of the protein partners of these human specific isoforms of the RNA polymerase II subunit hRPB 11 (POLR2J) has been established. Functional characteristics of the uncovered protein partners of hRPB 11balpha and hRPB 11calpha isoforms clearly indicate that these isoforms, similarly to the main (major) subunit hRPB11a, are components of the distinct transcription complexes participating not only in the transcription of the specific DNA matrices, but involving also in the later stages of mRNA biogenesis. The RNA polymerase I-III common subunit hRPB6 (POLR2F) and basal component of the exon-exon junction complex Y14 (RBM8A) have been found among the protein partners of the isoforms hRPB 11bbeta and hRPB 11cbeta together with a number of proteins involved in the biogenesis of microRNAs, including a novel, not previously described variant of the microRNA processing nuclease DROSHA, which indicates the existence of a special coordination between processes of transcription and RNA interference in the nuclei of human cells.