Stranger Twins: A Tale of Resemblance and Contrast Between VAP Proteins.

When considering the vesicle-associated membrane protein-associated protein (VAP) family, major receptors at the surface of the endoplasmic reticulum (ER), it appears that VAP-A and VAP-B paralogs largely overlap in structure and function, and that specific features to distinguish these two proteins hardly exist or are poorly documented. Here, we question the degree of redundancy between VAP-A and VAP-B: is one simply a backup plan, in case of loss of function of one of the two genes, or are there molecular and functional divergences that would explain their maintenance during evolution?