Final answer:
Calnexin contains a transmembrane helix which allows it to span the membrane, while Calreticulin has a calcium-binding capacity but no transmembrane helix; both are essential for glycoprotein folding.
Step-by-step explanation:
In regards to the proteins Calnexin and Calreticulin, Calnexin has a transmembrane (TM) helix, which allows it to anchor and span the membrane of the endoplasmic reticulum. Calreticulin, on the other hand, doesn't have a transmembrane helix but instead has a calcium-binding domain. Both proteins are integral to the proper folding of glycoproteins within the cell. Calnexin and Calreticulin play a role in quality control, ensuring that only properly folded proteins move forward in the secretion pathway.