SLC30A2 and Zinc deficiency: Notably, mutation of a single residue in the HCH motif of ZnT2 (H54R) was directly linked with transient neonatal zinc deficiency (TNZD), further indicating the significance of this motif in the function of SLC30 family of zinc transporter (Figure 4—figure supplement 1; Chowanadisai et al., 2006). It also worth noting that similar HCH motif has been found in the C-terminus of copper importer Ctr1 that can bind Cu2+ and is important for the regulation of Ctr1 activity (Maryon et al., 2013).