Characterization of mouse T cell surface ADP ribosyl transferase 2.1

Abstract

ADP-ribosylation is a post-translational modification of certain proteins by addition of the ADP-ribose moiety of NAD to a target protein by ART (ADP-ribosyltransferase) activity. The two different ARTs can be classified in terms of ADP-ribosylated production, mono-ART and poly-ART. The enzymatic activities are extremely variable within these ARTs if compared between prokaryotes and eukaryotes. The ARTs’ enzymatic activities are different even from one species to another within eukaryotes. The ADP-ribosylation of the certain proteins generally changes the proteins’ biological functions significantly. For example, cholera toxin and the related heat-labile enterotoxin of Escherichia coli ADP-ribosylate G proteins in epithelial cells in the intestine and alter critical metabolic pathways of the host leading to the death of the host. The differently classified eukaryotic ARTs have different cellular localizations. More than five different ecto-ARTs, designated ART1-ART5, which distantly resemble ADP-ribosylating bacterial toxins, have been cloned from human and other mammals. ART1-ART4 are glycosylphosphatidylinositol (GPI)-anchored cell surface proteins, while, ART5 is a secretory soluble enzyme. There are a series of ARTs throughout mammalian tissues. Different tissues or systems have different ARTs. Although these ARTs have been studied for a long time, the full biological functions of these ARTs are not completely understood. One of the most well understood ARTs is ART 2 expressed in rats, the BBDR and BBDP strains. These two different strains have almost the same genetic background except for a few loci in their chromosomes. One of these genes is ART 2. BBDR rats express ART 2 on the surface of T cells while BBDP rats do not, and BBDR is resistant to diabetes type I while BBDP is prone to diabetes type I. There is little doubt that ART 2 is involved in modulation of diabetes type I development in animal models like the Bio-Breeding rat, BBDP stain. However, t...