In contrast, biotinylated MET was readily detected in A549 cells upon labeling of intact cells, as shown by the biotin-labeled α-chain (Fig. 4d, lane 3).
Upon labeling the accessions with their origin from the Upper Bahau river, lower Bahau river, and Kayan river, there is one cluster of 25 landraces that was found only in the more remote Bahau river region, while the remainder of the clusters contained a mixture of accessions from all three regions (Fig. 2).
Thus, the structural integrity of the TNH complex after labeling was checked by native MS to see whether the complex has dissociated upon labeling.
Several fluorogenic substrates showed quenching efficiencies greater than 95%%, which corresponds to a ∼20-fold increase in the fluorescence signal upon labeling the SNAPf protein.
Upon labelling the cells with H-cholesterol to monitor its conversion by ACAT into H-cholesteryl esters, we found significantly higher ACAT activity in the Ps-mutant MEFs (up to ∼2.5-fold over controls).
Roberts and Evans [ 5] demonstrated that ATP-induced currents in the human P2X1 receptor mutant G321C (corresponding to Gly in rat P2X2) were markedly impaired upon labelling with thiol-reactive agents, and suggested that this residue might be involved in ion permeation.
By capitalizing on the remarkable sensitivity of mass spectrometry, the compound(s) to be discovered do not need to be present at bioactive concentrations, they only need to be detectable upon labeling.
A slight but an insignificant increase of α2,6-linked sialic acids upon labelling with SNA was also observed and as expected, the binding of both lectins was abolished upon sialidase treatment that removed the sialic acid residues at the cell surface of both the cell lines (results not shown).
However, neuronal survival does not seem to be altered in aged animals since birthdating experiments based on the comparison of BrdU positive neurons at different times upon labeling in old and young animals showed that the proportion of neurons dying after birth is unchanged [ 56- 58].
Others say an agreed-upon label would confer a sense of historical status.
