The 50S ribosomal subunit is a component of the ribosome, which is essential for protein synthesis in cells. It is part of the larger 70S ribosome found in prokaryotes, such as bacteria. The 50S subunit works alongside the smaller 30S ribosomal subunit to facilitate the translation of messenger RNA (mRNA) into proteins. This subunit is composed of ribosomal RNA (rRNA) and proteins, forming a complex that helps in the assembly of amino acids into polypeptide chains. The 50S subunit plays a crucial role in the peptidyl transferase activity, which links amino acids together during protein synthesis.