Question

1. Explain what ZIP and ZnT proteins are and what they do to Zn concentrations.

Answer 1

Zinc is transported across the cell membrane in the form of Zn​​​​​2+. For this Zinc transporter proteins are present in the Cell membrane. They are of two types.

1. Zinc transporter ,ZnT ,or solute carrier 30 .

This controls efflux of zinc from cytoplasm out of the cell and from cytoplasm into vesicles. So it decreases the concentration of zinc in the cytoplasm. ZnT moves zinc out of cell membrane in exchange of H +.

2. Zinc importer , ZIP , or solute carrier 39A.

It controls influx of zinc into cytoplasm from outside the cell and from vesicles. ZIP is a HCO​​​​3​​​​​​​​-  symporter.ie zinc and bicarbonate move towards the cytoplasm together to maintain the ionic balance.

So to maintain homeostasis and normal cellular functioning when Zn concentration increases inside the cytoplasm ,then ZnT moves the Zn​​​​​2+ out of cytoplasm. Conversely when concentration of Zn 2+ is more outside in the extracellular component , then ZIP protein transfer it inside the cell ,into cytoplasm.