Cloning and characterization of the human ribosomal protein S21 gene

: A full-size functional gene encoding the human ribosomal protein S21 was cloned and characterized. Its nucleotide sequence, exon-intron organization, and transcription initiation site were determined. The gene comprises 1417 bp and is composed of six exons and five introns. Like most known genes of mammalian ribosomal proteins, it lacks the canonical TATA- and CAAT sequences in the promoter region and harbors potential binding sites for transcription factors both upstream and downstream the transcription initiation site. The first intron of the rpS21 gene is located in the 5'-untranslated region. The transcription initiation site is at a 53-bp distance from the ATG codon, and the initiation cytidine is surrounded by polypyrimidine tracts. The 5'-flanking region contains two repeats belonging to the Alu-S and Alu-J families.