ATP Binding Cassette Transporter C4 (ABCC4)

ABCC4, also known as MRP4, belongs to a large family of transmembrane proteins involved in active transport of substrates out of cells. ABCC4 acts as an independent regulator of intracellular cyclic nucleotide levels and as a mediator of cAMP-dependent signal transduction to the nucleus.

The insertion was attributed to 2 additional exons, designated 1a and 1b, that produced premature termination codons (PTCs). A comparison of human, monkey, and rodent ABCC4 genes revealed that these same PTC-producing exons were also highly conserved in evolution. In vitro inhibition of protein synthesis (using puromycin or anisomycin) selectively reduced nonsense-mediated mRNA decay of PTC-containing ABCC4 transcripts in all cell lines tested.