Question

what are the basic differences between all the immunoglobulins?

Answer 1

Structurally, immunoglobulins are integral membrane proteins. Inside the cell one end of the protein is anchored to the cytoskeleton. The other end sticks out through the cell membrane into the extracellular matrix. That part outside the cell is composed of a few modular, repeated domains which are very similar but not identical in sequence and structure. Basically, the extracellular domains vary. They have varying copies of specific domains linked together like a paper clip chain.

Interestingly, Immunoglobulin like domains - literally "Ig like domains" in the literature - form the extracellular portions of some transmembrane receptor tyrosine kinases...