C4 antisense RNA (c4)

C4 antisense RNA is a small non-coding RNA molecule originally identified in certain bacteriophages such as P1 and P7 that infect *Escherichia coli*. It regulates the *ant* (anti-repressor) gene through a specific antisense mechanism: C4 antisense RNA has two regions that bind complementary sequences of its DNA targets, resulting in repression of the anti-repressor gene immediately downstream. Its biological role is restricted to bacteriophage regulatory circuits rather than those of mammals or other eukaryotes. Although bioinformatics have found homologs in other phages and in bacterial genomes, there is no evidence for a human gene or therapeutic target named “C4B antisense RNA 1” or “C4B-AS1”. The closest related concept in humans is the complement component 4B (C4B) gene associated with immune function and certain diseases, but this is genomic and functionally unrelated to the phage c4 antisense RNA[1][2].

Other names

c4 antisense RNAc4C4B antisense RNA 1 (uncommon, non-standard alias; not used in the literature)