The characterization of glutathione S-transferases from rat olfactory epithelium

Abstract

The glutathione S-transferases (GSTs) of rat olfactory epithelium have been characterized with regard to substrate specificity and subunit composition and compared to those of the liver. The presence of cytosolic GST activity in rat olfactory epithelium was confirmed and, using 1-chloro-2,4-dinitrobenzene as substrate, was found to be approximately one-third that of the liver. Olfactory microsomal GST activity was greater than that of liver microsomes and could be activated by treatment with the sulphydryl agent N-ethylmaleimide. The subunit and isoenzyme profile of GSTs in the olfactory epithelium was investigated using a number of techniques. (1) Olfactory GSTs were characterized using a range of relatively subunit-specific substrates. Activities ranged from 40-90% of those found in liver. Most noticeable was the extremely low olfactory activity with the substrate specific for subunit 1. (2) Immunoblotting with antibodies against specific rat hepatic GSTs confirmed the presence of a number of subunits and the absence of subunit 1. (3) F.p.l.c. chromatofocusing and reverse-phase h.p.l.c. indicated that the cytosolic GST profile of olfactory epithelium is unique and is made up of subunits 2, 3, 4, 7, 8 and 11 with subunits 3 and 4 predominating. There is an absence of isoenzymes containing subunit 1.

Drug Transport into the Mammalian Brain: The Nasal Pathway and its Specific Metabolic Barrier

“…The occurrence of six different GST isoenzymes able to metabolise several odorant molecules has been demonstrated in this tissue (Ben-Arie et al, 1993;Banger et al, 1993). As is the case for EH, both soluble and microsomal GST have been described, and the olfactory microsomal GST displays activities that reach the same levels as the hepatic isoform (Banger et al, 1993).…”

“…As is the case for EH, both soluble and microsomal GST have been described, and the olfactory microsomal GST displays activities that reach the same levels as the hepatic isoform (Banger et al, 1993). The physiological role of olfactory GSTs remains unclear, but it has been suggested that they may have a role in olfaction, by rapid cleaning of odorants to maintain acuity of olfaction (Banger et al, 1996).…”

Immunohistochemical demonstration of salmon olfactory glutathione S-transferase class pi (N24) in the olfactory system of lacustrine sockeye salmon during ontogenesis and cell proliferation

“…Based on its biochemical characteristics, cytosolic GST is usually divided into four classes: alpha, mu, pi, and theta (Mannervik and Danielson 1988;Meyer et al 1991). Previous studies have shown high expression of GST protein and/or mRNA in the olfactory epithelium of rats (Banger et al 1993;Ben-Arie et al 1993). Immunoreactivities of GST were localized in the sustentacular cells and Bowman's gland of the olfactory epithelium in adult rats (Banger et al 1994) and rats during development (Krishna et al 1994).…”

Expressions of the multidrug resistance-related proteins in the rat olfactory epithelium: A possible role in the phase III xenobiotic metabolizing function

“…Since several phase I and phase II xenobiotic metabolizing enzymes were already detected in the olfactory epithelium of the mammals, the xenobiotic metabolizing system is considered to play important roles in the chemical homeostasis of the olfactory epithelium [2,4,15]. In particularly, the existences of olfactory specific isoforms were reported in cytochrome P450 as phase I enzyme [17] and UDP-glucuronosyl transferase as phase II enzyme [14] in mammalian olfactory epithelia.…”