A genomic perspective on membrane compartment organization

Now that whole genome sequences are available for many eukaryotic organisms from yeast to man, we can form broad hypotheses on the basis of the relati ve expansion of protein families. To investigate the molecular mechanisms r esponsible for the organization of membrane compartments, we identified mem bers of the SNARE, coat complex, Rab and Sec1 protein families in four euka ryotic genomes. Of these families only the Rab family expanded from the uni cellular yeast to the multicellular fly and worm. All families were expande d in humans, where we find 35 SNAREs, 60 Rabs and 53 coat complex subunits. In addition, we were able to resolve the SNARE class of proteins into four distinct subfamilies.