Amino-acid permease that coordinates external nitrogen source response and morphogenesis (PubMed:12949183, PubMed:21764911, PubMed:28028545). Is capable of transporting several structurally unrelated amino acids such as leucine and phenylalanine, though with a lower capacity than the GAP2 and GAP6 permeases (PubMed:21764911). Has citrulline import activity (PubMed:12949183). GAP1 is also able to transport thialysine, and thus probably also lysine (PubMed:21764911). Functions as a sensor via detection of some amino acids including methionine, leading to a rapid activation of trehalase, a downstream target of PKA (PubMed:21764911). Expression is under control of the CSY1 amino-acid sensor (PubMed:28028545). Expression is induced by N-acetylglucosamine (PubMed:12949183). Expression is also regulated by CPH1-mediated RAS1 signaling but is independent of EFG1 (PubMed:12949183). Induced during biofilm development (PubMed:21414038, PubMed:22265407, PubMed:23572557). Induced upon internalization by host macrophages (PubMed:15470236). Expression is down-regulated by growth in alkaline conditions (PubMed:15554973). Expression is also controlled by the nitrogen-dependent GATA-type transcriptional activator GAT1 (PubMed:14617156). Decreases two fold the citrulline uptake (PubMed:12949183). Leads to defective hyphal formation in solid hyphal-inducing media and exhibits less hyphal clumps when induced by N-acetylglucosamine (PubMed:12949183). Belongs to the amino acid-polyamine-organocation (APC) superfamily. YAT (TC 2.A.3.10) family.