Zinc is the second most prevalent metal element present in living organisms, and control of its concentration is pivotal to physiology. The amount of zinc available to the cell cytoplasm is regulated by the activity of members of the SLC39 family, the ZIP proteins. Selectivity of ZIP transporters has been the focus of earlier studies which provided a biochemical and structural basis for the selectivity for zinc over other metals such as copper, iron, and manganese. However, several previous studies have shown how certain ZIP proteins exhibit higher selectivity for metal elements other than zinc. Sequence similarities suggest an evolutionary basis for the elemental selectivity within the ZIP family. Here, by engineering HEK293 cells to overexpress ZIP proteins, we have studied the selectivity of two phylogenetic clades of ZIP proteins, that is ZIP8/ZIP14 (previously known to be iron and manganese transporters) and ZIP5/ZIP10. By incubating ZIP over-expressing cells in presence of several divalent metals, we found that ZIP5 and ZIP10 are high affinity copper transporters with greater selectivity over other elements, revealing a novel substrate signature for the ZIP5/ZIP10 clade. Supplementary Information The online version contains supplementary material available at 10.1007/s10534-022-00474-6.

The purpose of this exploratory, mixed-methods study was to investigate the relationship between nontraditional undergraduate students' curiosity and their experiences researching a topic. The author collected and analyzed survey data and annotated bibliography rubric scores from 59 students at a private, liberal arts university and conducted in-depth interviews to gather a fuller picture of the students' curiosity. Based on the study's findings, librarians and professors should create opportunities for students to select research topics to which they have a personal connection while intentionally offering supportive feedback to students as they refine their topics to reduce anxiety and frustration.

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