PH is dissolved in water, the pH will be greater than 7. A solution of a strong acid, such as hydrochloric acid, at concentration 1 mol dm has a pH of 0. A solution of a strong alkali, such as sodium hydroxide, at concentration 1 mol dm, has a pH of 14. Thus, measured pH values will lie mostly in the range 0 to 14, though negative pH values and values above 14 are entirely possible. Since pH is a logarithmic scale, a difference of one pH unit is equivalent to a tenfold difference in hydrogen ion concentration. <br> The pH
6TMS neutral amino acid transporter family multidrug efflux pump of the RND superfamily (TC #2.A.6.2)) and the "mar" regulon itself, and (3) MarB, a small protein of 71 amino acyl residues of unknown function. A periplasmic binding protein, MppA, essential for the uptake of the cell wall murein tripeptide, L-alanyl-γ-D-glutamyl-"meso"-diaminopimelate via the Opp permease, regulates "mar" regulon expression. Loss of MppA causes overproduction of MarA which activates "acrAB", causing pleiotropic drug resistance. MppA probably functions upstream of MarA in a signal transduction pathway that negatively controls expression of the "marRAB" operon. 6TMS neutral amino acid transporter family The 6TMS Neutral Amino Acid Transporter (NAAT) Family (TC#