Molecular cloning and characterization of the porcine Ero1L and ERp44 genes: potential roles in controlling energy metabolism.

Disulfide bond formation is a pivotal step in the maturation and release of secretory proteins that is controlled by specific endoplasmic reticulum (ER) resident enzymes. An important element in this process is Ero (ER oxidoreduction), a glycosylated flavoenzyme tightly associated with oxidative protein folding that lacks the known ER retention motifs. ER resident protein 44kDa (ERp44) is an ER resident protein that mediates ERo1 localization in ER and also prevents the secretion of unassembled cargo proteins with unpaired cysteine. These proteins are not only the key participants in the disulfide-bond formation process, but they also control the secretory pathway on both qualitative and quantitative levels. Here, we cloned full-length cDNA sequences of the porcine Ero1L (1448bp) and ERp44 (1361bp) genes. Isolation and characterization of their genomic sequences revealed that Ero1L contains 16 exons and 15 introns almost 150 kp in length, whereas ERp44 contains 12 exons and 11 introns more than 140 kp in length, and they are located on porcine chromosome 1q21 and 1q29, respectively. Tissue distribution analysis of the two genes revealed extremely high expression in adipose tissue, and the topology of their phylogenic tree indicates a high degree of conservation among different species. We looked at transcription factors binding sites in the 5'-flanking regions of Ero1L and ERp44, and many adipose differentiations related factors reflect the tight relationship to energy metabolism.