SLC31A1, also known as CTR1, COPT1 and solute carrier family 31 member 1, is a high-affinity copper transporter found in the cell membrane of human cells. It plays a crucial role in maintaining copper homeostasis within the body and functions as a homotrimer to influence dietary copper absorption in the cell membrane (PMID: 37853210; 28507097). SLC31A1 has three putative transmembrane domains, with an N-terminus located extracellularly and a C-terminus located intracellularly (PMID: 12827356). SLC31A1 can be detected a a 28 kDa band corresponding to glycosylated hCTR1 monomer, and a 24 kDa band that is unglycosylated hCTR1. In some membrane preparations a C-terminal degradation product of 17 kDa is also seen (PMID: 16135512). Additionally, SLC31A1 may also resolve as a 30 to 35 kDa and a 60 to 70 kDa protein on immunoblots, forming oligomers corresponding to the expected size of a homotrimeric complex (PMID: 12827356).