An evolutionarily conserved U5 snRNP-specific protein is a GTP-binding factor closely related to the ribosomal translocase EF-2.

摘要: The driving forces behind the many RNA conformational changes occurring in spliceosome are not well understood. Here we characterize an evolutionarily conserved human U5 small nuclear ribonucleoprotein (snRNP) protein (U5‐116kD) that is strikingly homologous to ribosomal elongation factor EF‐2 (ribosomal translocase). A 114 kDa (Snu114p) U5‐116kD was identified Saccharomyces cerevisiae and shown be essential for yeast cell viability. Genetic depletion of Snu114p results accumulation unspliced pre‐mRNA, indicating splicing vivo. Antibodies specific inhibit pre‐mRNA a HeLa extract vitro . In cells, located nucleus co‐localizes with snRNP‐containing subnuclear structures referred as speckles. G domain U5‐116kD/Snu114p contains consensus sequence elements G1–G5 important binding hydrolyzing GTP. Consistent this, can cross‐linked specifically GTP by UV irradiation snRNPs. Moreover, single amino acid substitution G1 motif Snu114p, expected abolish GTP‐binding activity, lethal, suggesting probably hydrolysis function U5‐116kD/Snu114p. This date first evidence domain‐containing plays role process.