Identification of a novel human Acyl-CoA binding protein isoform with a unique C-terminal domain

Seven isoforms of the multifunctional human Acyl-coenzyme A binding protein (ACBP) have been characterized so far. Through ab initio analysis of expressed sequence tag (ESTs), we identified a novel high-abundant ACBP splice variant ACBP1e encoding an ACBP isoform with a unique C-terminus of 81 amino acid residues. Bioinformatic analysis shows that this domain is evolutionary conserved and shares no significant homology with other known proteins, and its function is not known. Quantitative RT-polymerase chain reaction (PCR) revealed that ACBP1e is predominantly expressed in adipose tissue and hippocampus. Protein expression studies showed perinuclear clustering of ACBP1e. These clusters were not seen in ACBP1e mutants with an altered putative subtilisin/kexin isozyme-1 cleavage site within the C-terminus, indicating that this domain is required for proper localization of ACBP1e. Conclusively, we identified a novel ACBP isoforms with an unique C-terminal domain encoded by a high-abundant splice variant.