Question

What happens to ${\mathit{K}}^{\mathbf{+}}$transport by valinomycin when the membrane is cooled below its transition temperature?

Short answer

The transport of $K^{+}$ion stops through valinomycin when the temperature of the membrane reaches below the transition temperature.

Step-by-step solution

Introduction

Valinomycin is a well-studied ionophore that binds specifically to a $K^{+}$ion. It's a cyclic ionophore withester linkage, peptide bonds, and D and L-amino acids.

Changes occur in  transport

Valinomycin is a channel-formingionophorethat creates transmembrane channels or pores that allow chosen ions to flow through. When the membrane is cooled below the transition temperature, the lipids become immobilization in agel-like state. It makes theionophore-K complex unable to diffuse through the membrane causing the transport to be terminated.