Often, ubiquitin is not only conjugated as a single moiety, but rather forms chains of multiple ubiquitin molecules linked via isopeptide bonds between the C-terminal glycine residue of ubiquitin and one of the seven internal lysine residues of the preceding ubiquitin in the chain.
However, an advanced option has now been added to provide the range of the ligand residue numbers to be considered as a single moiety during the entire protocol.
Ub is conjugated either as a single moiety or as polyubiquitin chains linked through K48, K63, or other K residues of Ub with different functional consequences.
Therefore the addition of a single hydroxymethyl moiety within the center of the CDR3β loop can dramatically alter TCR sensitivity.
Hence, although TRC40 binding is relatively tolerant of the addition of a single PEG-5000 moieto thethe Sec61β TA-region, a subsequent step of the membrane insertion process appears much more sensitive to the precise location of such a probe and PEGylation of Cys appears not to be tolerated.
To assess the effect of a single phosphate moiety on the aggregation kinetics of strand E, the phosphopeptide variant p9Y containing a single phosphotyrosine at position 9 was prepared and its aggregation kinetics were measured.
This pathway produces UDP- N-acetyl-glucosamine (UDP-GlcNAc), a substrate for N- and O-glycosylation, as well as for O-GlcNAcylation, which consists of the addition of a single GlcNAc moiety to serine and threonine residues (for a review, see Bouche et al [ 12]).
Notably, whereas Lys 48-linked Ub chains target proteins for proteasomal degradation [1], conjugation of a single Ub moiety to one (monoubiquitination) or more (multiubiquitination) Lys residues of the substrate protein has been proposed to be sufficient as internalization and endocytic sorting signal in yeast [2], [4].
Although linkage of a single Ub moiety to Gap1 is a sufficient signal for its internalization from the cell surface [9], the permease is modified by short Ub chains built through linkage to the K63 residue of Ub [31].
Notably, ω-transaminases can be exploited for regioselective conversion of a single ketone moiety in a di- or even triketone system in a more complex molecule.
