Role of Transfer RNA in the Degradation of Selective Substrates of the Ubiquitin- and ATP-Dependent Proteolytic System

Abstract

Degradation of intracellular proteins via the ubiquitin (Ub) pathway involves several steps. Initially, Ub is covalently linked to the protein substrate in an ATP-dependent reaction. Following Ub conjugation, the protein is selectively degraded with the release of free and reusable Ub. Ub modification of a variety of protein targets in the cell appears important in a number of basic cellular functions. For example, modification of core nucleosomal histones may regulate gene expression at the level of chromatin structure. Ub attachment to cell surface proteins can play a role in the process of cell-cell interaction and adhesion. Conjugation of Ub to other, yet to be identified, protein(s) is probably involved in the progression of cells from one stage to another in the cell cycle.