Michael T. Henzl Michael T. Henzl Biochemical and Biophysical Characterization of Proteinsfrom the Mammalian Auditory Organ. After nearly three decades of investigation, the underlying structural basis for this variation remains incompletely understood. The parvalbumin family includes a and b sub-lineages.
Mammals express one isoform from each lineage.
Presumably, the two mammalian parvalbumins function in this capacity in the cochlea, or inner ear. However, it is not clear why the IHC and OHC would utilize distinct parvalbumin isoforms. The solution to this puzzle most likely resides in the disparate physiological roles of the two sensory cell types and in the disparate metal ion-binding properties of the two mammalian parvalbumins. Recent data suggest that parvalbumin divalent ion affinities are sensitive to the identity and concentration of monovalent cations and that the degree of sensitivity is isoform dependent. Although their physiological functions are unknown, OCP2 displays extreme homology to Skp1, a participant in ubiquitin-mediated protein degradation.