PH PH In chemistry, pH () is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion. At 25 °C, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. The neutral value of the pH depends on the temperature, being lower than 7 if the
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#