Protein sequence evidence for monophyly of the carnivore families Procyonidae and Mustelidae

Abstract

The amino acid sequence of the eye lens protein α-crystallin A of the ring-tailed cat, Bassariscus astutus, has been determined. The sequence of the Bassariscus αA chain, which is 173 residues long, was compared with the previously determined set of 41 mammalian αA sequences. Among the investigated carnivores (dog, cat, sloth bear, American mink, gray seal, and California sea lion) the Bassariscus αA sequence exclusively shares two amino acid replacements with the αA chain of the mink, Mustela vison: 7 His → Gln and 61 Ile → Val. The Mustela and Bassariscus αA sequences differ at only three positions and have no replacements in common with any of the other investigated carnivore αA chains. Furthermore, the replacement 7 His → Gln has only been found in three-toed sloth, whereas 61 Ile → Val occurs scattered in three other taxa: pig, rhinoceros, and prosimians. It thus is most parsimonious to join Bassariscus and Mustela - and consequently their respective families, Procyonidae and Mustelidae - as sister groups in the phylogenetic tree of mammalian αA sequences.