<p>A number of eukaryotic and archaeal ribosomal proteins can be grouped on the basis of sequence similarities. One of these families includes yeast S7 (YS6); archaeal S4e; and mammalian and plant cytoplasmic S4 [<cite idref="PUB00000844"/>]. Two highly similar isoforms of mammalian S4 exist, one coded by a gene on chromosome Y, and the other on chromosome X. These proteins have 233 to 264 amino acids.</p><p>This entry represents the conserved site of the ribosomal protein S4e that is found at the N-terminal region.</p>