Enzyme recruitment substrates

Morris, M.E. and Pang, K.S. (1987) Competition between two enzymes for substrate removal in liver modulating effects due to substrate recruitment of hepatocyte activity. Journal of Pharmacokinetics and Biopharmaceutics, 15, 473-496. 

Figure 2. Protein interaction domains are used by E3 protein-ubiquitin ligases to recruit substrates for ubiquitination, as well as E2 enzymes. Ubiquitination targets contain specific peptide motifs which bind interaction domains in the E3 protein/complex. These interactions can require phosphorylation on tyrosine (pTyr) or threonine (pThr), or the presence of proline-rich motifs (PPXY). The papilloma vims E6/E6AP complex can recognize substrates that contain PDZ domains, which bind a C-terminal motif in the E6 viral protein. See text for details.

Copley S. D. (1998) Microbial dehalogenases enzymes recruited to convert xenobiotic substrates. Curr. Op. Chem. Biol 2, 613-617. 

GPIS is presumed to be the catalytic center of the enzyme since it shares sequence homology with a family of cysteine proteases, one member of which has transamidase activity in vitro. Mutagenesis of a Cys-His catalytic dyad in human GPIS inactivates GPIT. The functions of the remaining subunits are unknown. It seems likely that they recruit substrates, or regulate substrate access to the catalytic site (S. Vainauskas, 2004, 2006). 

Wells, J.A., et al. Recruitment of substrate-specificity properties from one enzyme into a related one by protein engineering. Proc. Natl. Acad. Sci. USA 84 5167-5171, 1987. 

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