The MEL gene: a new member of the RAB/YPT class of RAS-related genes

The MEL gene was identified following transfection of NIH3T3 mouse fibroblasts with DNA from a human melanoma cell line. The human MEL gene has been localized to 19cen-p13.2, a region in which translocation breakpoints occur in a number of malignancies. We have identified and sequenced human and mouse MEL cDNA clones which show homology of 92% and 96% at the nucleotide and amino acid levels respectively. The predicted human MEL protein shows only six amino acid differences between it and the recently described dog RAB8 protein. All of these changes occur in the 30 amino acids at the C-terminal of these proteins. MEL is similar to the RAB/YPT proteins in the region corresponding to the putative effector domain, suggesting that they may interact with the same cellular substrates. However, MEL contains a C-terminal CAAX motif in common with the majority of the RAS superfamily, unlike YPT1 and the majority of the RAB proteins.