Structure/functional analysis of an Xq28 gene codifying for a new Endoplasmic Reticulum small protein.

Human chromosome Xq28 is a gene-rich region, which lies within the critical linkage interval for many human diseases. Here we report the structure/function analysis of a new Xq28 gene, FUNDC2 encoding a predicted small protein targeted to the endoplasmic reticulum (ER) with unknown function. Comparative sequences and chromosomal mapping indicates that FUNDC2 has duplicated copies located around peri-centromere of other human chromosomes therefore highlighting a phenomenon of paralogous genome evolution common to other Xq28 genes. FUNDC2 has ubiquitous expression in embryos and adult human tissues and its predicted protein shows high conservation from low organisms to primates suggesting that it could be member of a new family of functionally related genes. The deduced 189-amino-acid sequence appears rich of hydrophobic residues and lacks a signal-sequence for protein sorting or for targeting to membranes. However, subcellular fractionation and immunofluorescence localization studies suggest that FUNDC2 protein co-localize with ER proteins. Other functional studies are currently underway.