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).
References:
The copper interacting protein Atx1, that could be a copper chaparone protein or a copper efflux protein. It is of 70 aas with an N-terminal half that is more hydrophobic than the C-terminal half (Deng and Wang 2023).
Atx1 of Chlamydomonas reinhardtii
HMA domain-containing protein of 81 aas.
Atx1 homolog of Glycine max (Soybean) (Glycine hispida)
Copper transport protein, ATX1, of 76 aas.
ATX1 of Arabidopsis thaliana (Mouse-ear cress)
Copper transport protein, CCH, of 121 aa
CCH of Arabidopsis thaliana
ATOX1 (HOH1) copper chaparone/transport protein of 78 aas amd 0 TMSs. It is homologous to the N-terminal repeat sequences in Cu2+ ATPases (e.g., TC# 3.A.3.5.19; 28% identical and 51% similar). However, the proteins in this family are single domain proteins. Curcumin suppresses copper accumulation in non-small cell lung cancer by binding ATOX1 (Qin et al. 2024).
ATOX1 of Homo sapiens