transporterreceptor

Transporter receptor is a term used to describe membrane proteins that can both transport substrates across the cell membrane and act as receptors that initiate intracellular signaling in response to substrate binding. The more established term for this dual function is transceptor, and transporter receptors are often discussed in that context. These proteins can sense extracellular nutrients or ligands and trigger cellular responses even when transport into the cytosol is not required for signaling.

In yeast and plants, transceptors are well documented. General amino acid permeases such as Gap1 in Saccharomyces cerevisiae act as transceptors, conveying amino acid availability to signaling pathways that regulate growth and metabolism. Other amino acid or nutrient transporters, including Can1, Dip5, and Gnp1 in yeast, also display signaling roles. In plants, nitrate transporters CHL1/NRT1.1 and ammonium transporters AMT1 have been described as transceptors that couple transport to nutrient signaling, influencing root development and nutrient uptake regulation.

In mammals, certain solute carriers (SLCs) have been implicated in signaling functions in addition to transport. For example, some amino acid transporters participate in nutrient-sensing pathways that regulate mTOR and related networks, highlighting the broader relevance of transporter-mediated signaling in animal cells.

Mechanistically, transceptors often transduce signals through conformational changes upon ligand binding, recruitment of signaling partners, and activation of kinases or nutrient-sensing pathways. They may initiate signaling with or without substrate translocation and can be subject to regulation by endocytosis or altered transport activity.

See also: transporter, receptor, transceptor, nutrient signaling, TOR pathway.