Effect of poly-L-lysine on potassium fluxes in red beet tissue

Poly-L-lysine concentrations (10(-6) M) which cause slight leakage of pigment from beet cells completely disrupt the kinetics of(*)K (labeled) absorption at 25°C in the range 0.01 to 50MM KCl. Lower concentrations of polylysine (10(-7) to 10(-9) M) interfere with potassium fluxes at both cell membranes, initially increasing efflux across the plasma membrane and decreasing the capacity of the cytoplasm to retain ions during flux experiments at 2°C. At 25°C, these concentrations of polylysine increase(*)K (labeled) absorption from 0.2MM KCl, but not from 10MM KCl. These responses are discussed in relation to ion transport via the three-compartment in-series model proposed for plant cells. Particular emphasis is placed on the role of the plasma membrane in K transport from solutions of low concentration.