RPL5 Human

Ribosomal Protein L5 (RPL5) is a crucial component of the large 60S ribosomal subunit in eukaryotic cells. It plays a significant role in ribosome biogenesis, which is essential for protein synthesis and cell growth. RPL5 is known for its involvement in the nucleocytoplasmic transport of 5S ribosomal RNA (rRNA) and its participation in the assembly of ribosomal subunits .

RPL5 is a 297-amino acid protein that localizes in both the cytoplasm and the nucleus of eukaryotic cells, with a particular accumulation in the nucleoli . The protein contains defined nuclear localization and export signals, which facilitate its transport between the nucleus and the cytoplasm . Specifically, the nuclear import and nucleolar localization signals are mapped to amino acids 21–37, while the carboxyl-terminal residues at positions 255–297 serve as additional nuclear/nucleolar targeting signals .

One of the primary functions of RPL5 is to bind specifically to 5S rRNA, a critical component of the 60S ribosomal subunit . This binding is essential for the nucleocytoplasmic transport of 5S rRNA and the assembly of ribosomal subunits. RPL5 also plays a role in the formation of ribonucleoprotein particles, which are complexes of RNA and protein that are not associated with ribosomes .

Ribosome biogenesis is a complex process that occurs in the nucleolus, a subnuclear compartment where ribosomal RNA (rRNA) is transcribed and ribosomal subunits are assembled . The 5.8S, 18S, and 28S rRNAs are synthesized by RNA polymerase I in the nucleolus, while 5S rRNA is transcribed by RNA polymerase III in the nucleoplasm . Ribosomal proteins, including RPL5, are encoded by mRNAs synthesized by RNA polymerase II. After translation, these proteins are imported from the cytoplasm into the nucleolus for the assembly of the 40S and 60S ribosomal subunits, which are then exported to the cytoplasm .

Mutations in RPL5 have been associated with Diamond-Blackfan anemia (DBA), a congenital disorder characterized by a failure to produce sufficient red blood cells . This condition, known as a ribosomopathy, highlights the critical role of RPL5 in ribosome biogenesis and cellular function .