Charge-Transport Characteristics of a Plasma Membrane Proton Pump

Abstract

In the mycelial fungus, Neurospora,the plasma membrane—like that of most other non-animal cells—is organized in a “chemiosmotic” fashion (Slayman, 1974; Eddy, 1978). This means that the major expenditure of metabolic energy at the membrane occurs via a proton efflux pump, which creates a standing difference of eletrochemical potential for protons (\(\vartriangle {{\tilde{\mu }}_{{{H}^{+}}}}\)). And it is this \(\vartriangle {{\tilde{\mu }}_{{{H}^{+}}}}\) that supplies energy for most other transport processes. A similar arrangement is found in animal cells, but there the major transport energy is used to create a \(\vartriangle {{\tilde{\mu }}_{N{{a}^{+}}}}\), which in turn drives other processes. (The structure and chemical properties of the membrane ATPase, which underlies H⁺ pumping in Neurospora,are described in Chapter 61.)