Phosphate Absorption Rates and Adenosine 5′-Triphosphate Concentrations in Corn Root Tissue

The correlations between ATP concentration in corn (Zea mays) root tissue and the rate of phosphate absorption by the tissue have been examined. Experimental variation was secured with 2,4-dinitrophenol, oligomycin, mersalyl, l-ethionine, 2-deoxyglucose, N(2) gassing and inhibition of protein synthesis. It is concluded that ATP could be the energy source for potassium phosphate absorption, but only if the transport mechanism possesses certain properties: oligomycin-sensitivity; creation of a proton gradient susceptible to collapse by uncouplers; phosphate transport via a mersalyl-sensitive Pi(-)-OH(-) transporter; good activity at energy charge as low as 0.4; short enzymatic half-life for the ATPase or phosphate transporter; a linked mechanism for K(+)-H(+) exchange transport, possibly electrogenic.