Uniporter

A uniporter is an integral membrane protein that is involved in facilitated diffusion. They can be either ion channels or carrier proteins.

Uniporter carrier proteins work by binding to one molecule of substrate at a time and transporting it with its concentration gradient. Uniporter channels open in response to a stimulus and allow the free flow of specific molecules. Both kinds of uniporters rely on passive transport, as they do not directly require cellular energy to function.

There are several ways in which the opening of uniporter channels may be regulated:

Uniporters are involved in many biological processes, including action potentials in neurons. Voltage-gated sodium channels are involved in the propagation of a nerve impulse across the neuron. During transmission of the signal from one neuron to the next, calcium is transported into the presynaptic neuron by voltage-gated calcium channels. Potassium leak channels, also regulated by voltage, then help to restore the resting membrane potential after impulse transmission.