9.B.462.  The Atx1 Copper Ion Chaparone or Transport Protein (Atx1) Family

The proteins of this family are annotated in UniProt as being copper chaparone proteins, but Deng and Wang 2023 have considered them to be copper efflux transporters. They are small proteins of about 70 - 80 aas in length with an N-terminal region that is moderately hydrophobic (may be an N-terminal TMS) and a C-terminal region that is more hydrophilic.  The Atx1 proteins are homologous to the N-terminal regulatory regions of copper P-type ATPases (TC# 3.A.3.5) which are thought to play a copper binding function, but not to be the actual transporter region of the ATPases. This same region seems to be homologous to mercuric ion binding proteins/transporters (see TC#s 1.A.72.3.1 and 1.A.72.3.4).