This brief paper addresses the problem of visually assessing the natural discriminability of the different subtypes that characterize class C G-Protein-Coupled Receptors, which are membrane proteins of interest in pharmacology, from diverse transformations of their primary amino acid sequences. Visualization, achieved using nonlinear dimensionality reduction techniques, is used as an exploratory tool to increase the interpretability of the data subtype structure. Combined with a quantitative estimation of subtype overlapping, this approach should be of help to experts in proteomics.Peer ReviewedPostprint (published version