We established that Jurkat 1G4 cells mirrored the 4D8 T cell clone in several key aspects: first, each cell type expresses both TPC1 and TPC2 isoforms as judged by RT-PCR, and second, NAADP/AM elicited Ca2+ responses in Jurkat 1G4 cells that were sensitive to Ned-19 and bafilomycin A1, consistent with acidic Ca2+ store involvement [ 22, 28].
This is consistent with the acidic character of boron which is likely to enhance interaction with the lone pairs of electrons in the water molecules.
We found that the shifts in EC50 caused by mutations at E698, E701, and D734 were consistent with these acidic residues playing a direct role in calcium coordination.
Consistent with the acidic peptide regions for Tiam1/2 binding, the electrostatic surface potential of the Tiam2 PHCCEx domain displays positively charged surfaces.
Upregulation of acid-inducible S. Typhimurium genes, such as pagC (Alpuche Aranda et al., 1992), cysB, adiY, marAB inside the macrophage vacuole is consistent with the acidic nature of the SCV (Rathman et al., 1996; Eriksson et al., 2003).
Consistent with the acidic region operating as a degron motif, recent work has revealed that a WNK4 knock-in mouse displaying a Gordon's syndrome mutation within this motif (WNK4 [D561A]) possesses markedly elevated levels of WNK4 in the kidney [ 7].
We find that the Arp5 subunit contacts the H2A-H2B dimer near its acidic pocket, consistent with recent cryoEM structures8,9, and this contact is diminished when the N-terminus of Arp8 is absent (Fig. 4a, b, d, and Supplementary Fig. 5).
On the other hand, metal phase decreased the isomerization temperature, which is consistent with enhanced the acidic strength of whole bi-functional catalysts especially for Co/zeolite catalysts.
Further, during sericin degradation, the alkalinity of the PBS that was initially adjusted to be pH 11 decreased to a level close to the neutral (Fig. 4c), indicating that the degraded products can neutralize the alkaline aqueous environment, consistent with the expected acidic nature of sericin's degraded products.
Considering that the ion is coordinated by carboxylate groups at positions of marked Na+/K+ selectivity (positions a, b and c), Na+/K+ selectivity in eukaryotic NaV channels is likely to arise from the coordination by conserved acidic residues, consistent with our previous proposition (Xia et al., 2013).
