The ATPC RNA motif is a conserved RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 structure found in certain cyanobacteria. It is apparently ubiquitous in Prochlorococcus marinus, and is present in many species in the genus Synechococcus

Synechococcus

Synechococcus is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 µm to 1.5 µm...

. The RNA is always found within an operon

Operon

In genetics, an operon is a functioning unit of genomic DNA containing a cluster of genes under the control of a single regulatory signal or promoter. The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo trans-splicing to create...

 encoding subunits of ATP synthase

ATP synthase

right|thumb|300px|Molecular model of ATP synthase by X-ray diffraction methodATP synthase is an important enzyme that provides energy for the cell to use through the synthesis of adenosine triphosphate . ATP is the most commonly used "energy currency" of cells from most organisms...

, and it is always located downstream of the gene encoding the A subunit of ATP synthase, and upstream of the C subunit

ATP synthase subunit C

ATPase, subunit C of F0/V0 complex is the main transmembrane subunit of V-type , A-type and F-type ATP synthases.ATPases are membrane-bound enzyme complexes/ion transporters that combine ATP synthesis and/or hydrolysis with the transport of protons across a membrane...

 gene. This location is consistent with a cis-regulatory element

Cis-regulatory element

A cis-regulatory element or cis-element is a region of DNA or RNA that regulates the expression of genes located on that same molecule of DNA . This term is constructed from the Latin word cis, which means "on the same side as". These cis-regulatory elements are often binding sites for one or...

, but also with a non-coding RNA

Non-coding RNA

A non-coding RNA is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA , non-messenger RNA and functional RNA . The term small RNA is often used for short bacterial ncRNAs...

 that is transcribed with the ATP synthase genes.

Simple RNA structures called stem-loop

Stem-loop

Stem-loop intramolecular base pairing is a pattern that can occur in single-stranded DNA or, more commonly, in RNA. The structure is also known as a hairpin or hairpin loop. It occurs when two regions of the same strand, usually complementary in nucleotide sequence when read in opposite directions,...

s have been reported in the ATP synthase operons of various cyanobacteria, but not structures such as the 3-stem junction that is the main feature of the ATPC RNA motif.