You have discovered a protein that transports Ca2+ ions up a concentration gradient, from the cytoplasm into the endoplasmic reticulum. No other ions move during this transport. Which type of transport protein does this appear to be?

Channel protein

Explanation:

A channel protein is one of types of membrane transport protein. It is a membrane transport protein that permits or allows the movement of ions, molecules through the membrane.

Channel proteins transport ions and molecules through the membrane passively by the means of facilitated diffusion.

Channel proteins are very specific to the kinds of ions that they transport through the membrane.

Examples of Channel proteins are: Calcium ion channel, Sodium ion channel e.t.c

2%? i tried finding the exact sorry if it's not 100% correct ; -;