Component of the ribosome, a large ribonucleoprotein complexresponsible for the synthesis of proteins in the cell. The smallribosomal subunit (SSU) binds messenger RNAs (mRNAs) and translates theencoded message by selecting cognate aminoacyl-transfer RNA (tRNA) molecules. The large subunit (LSU) contains the ribosomal catalyticsite termed the peptidyl transferase center (PTC), which catalyzes theformation of peptide bonds, thereby polymerizing the amino acidsdelivered by tRNAs into a polypeptide chain. The nascent polypeptidesleave the ribosome through a tunnel in the LSU and interact withprotein factors that function in enzymatic processing, targeting, andthe membrane insertion of nascent chains at the exit of the ribosomaltunnel. As part of the 5S RNP/5S ribonucleoprotein particle it is anessential component of the LSU, required for its formation and thematuration of rRNAs. It also couples ribosome biogenesis to p53/TP53activation. As part of the 5S RNP it accumulates in the nucleoplasm andinhibits MDM2, when ribosome biogenesis is perturbed, mediating thestabilization and the activation of TP53. Promotesnucleolar location of PML. [1-3]

MAQDQGEKENPMRELRIRKLCLNICVGESGDRLTRAAKVLEQLTGQTPVFSKARYTVRSFGIRRNEKIAVHCTVRGAKAEEILEKGLKVREYELRKNNFSDTGNFGFGIQEHIDLGIKYDPSIGIYGLDFYVVLGRPGFSIADKKRRTGCIGAKHRISKEEAMRWFQQKYDGIILPGK