One of two assembly initiator proteins, it binds directly to the 5'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit (By similarity). Required for optimal plastid performance in terms of photosynthesis and growth. Required for the translation of plastid mRNAs. Plays a critical role in biosynthesis of thylakoid membrane proteins encoded by chloroplast genes (PubMed:22900828). Part of the 50S ribosomal subunit. A number of isoforms are produced. According to EST sequences. Reduced plant size and pale green leaves. Belongs to the universal ribosomal protein uL24 family.