Allan et al. (1995) identified and characterized a previously unreported human gene located within the previously known cluster of apolipoprotein genes on chromosome 19: APOE , APOC1 , and APOC2 . On the basis of its location and its properties, the new gene was designated APOC4. Nucleotide sequence analysis of genomic DNA and liver cDNA clones revealed a 3.3-kb gene consisting of 3 exons and 2 introns. Its 3-prime terminus lies 555 bp upstream of APOC2, giving the 2 genes the same transcriptional orientation.

The promoter of the APOC4 lacks a typical TATA box, consistent with an apparent heterogeneity in transcription start sites. RNase protection analysis indicated relatively low apoC-IV mRNA levels in human liver, compared to apoC-II mRNA levels.