Figure 5.

Steps in identifying and classifying unknown solute carriers. (A) We extracted all human ORFs from Ensembl, (B) filtered out proteins with less than six predicted membrane α-helices, and (C) constructed multiple sequence profiles for the remaining sequences. (D) Simultaneously, a list of known solute carriers was extracted from public databases, and (E) again, for each protein sequence we created a multiple sequence profile. (F) We aligned a profile of each known solute carrier sequence with each of the human membrane protein profiles, resulting in a list of human membrane proteins that are similar to at least one known solute carrier. (G) Additional bioinformatics analysis, including construction of phylogenetic trees and detection of family-specific sequence motifs, allows us to identify high confidence predictions. (H) Finally, we verify our computational predictions experimentally by measuring the rate of substrate uptake into cells expressing tested transporters.