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

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Abstract
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, N2 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.