Ubiquitination cellular influence

Since the discovery of Ub (Schlesinger et al, 1975) more than 20 years ago, ubiquitination (Hershko et al., 1983) has become one of the cornerstones of covalent protein modification. An explosion of research in the area in the last 10 years has revealed biological roles for ubiquitination that rival the scope of phosphorylation. Because its traditional and best-characterized role is a fundamental biological process found in eukaryotes, namely, proteasome-dependent protein deg radation, it is not surprising that ubiquitination has such a broad cellular influence. More recendy, however, breakthrough discoveries in the field have revealed an even greater depth and versatility, several examples of which are encountered in the PRR pathway. 

A search for other agents to modify the dynamics of the Pr -> Pfr transformation, and in particular to influence differentially the reaction intermediates, focused on cellular constituents which presumably interact in vivo with phytochrome. Ubiquitin, an 8.5-kDa protein claimed to bind covalently in vivo to Pfr [160] has now also been found to interact in vitro with Pr in the absence of any other cellular constituent [161]. The protein... 

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