Which of the following protein is involved in intercellular connections?

Connexins is a protein involved in intercellular connections. It is an integral membrane proteins with four transmembrane domains, two small extracellular loops, a cytoplasmic loop and cytoplasmic N and C terminal tails. Connexins assemble into a hexamer in the plasma membrane forming a unit referred to as connexon or hemichannel. When two connexons on appositional cell membrane dock to each other, a gap junction channel is formed. Ref: Principles of Bone Biology By John P. Bilezikian, 3rd Edition, Page 430 ; Cell and Molecular Biology: Concepts and Experiments By Gerald Karp, 6th Edition, Page 239 ; Microbiology: An Introduction, 9th Edition By Toora, Page 455