Final answer:
Integrins are the integral membrane proteins with alpha and beta subunits that are crucial for connecting cells with the extracellular matrix (ECM). They play a significant role in cell adhesion, migration, differentiation, and survival by interacting with ECM components.
Step-by-step explanation:
The integral membrane protein that has alpha and beta subunits and is the most important family of proteins connecting cells with the extracellular matrix (ECM) is known as Integrins. Integrins are crucial for cell adhesion and signal transduction processes that dictate cell migration, differentiation, and survival. The specific interaction of integrins with ECM components such as fibronectin facilitates the attachment of cells to the ECM, influencing a host of cellular responses crucial during processes such as embryogenesis.
Other integral membrane proteins like Cadherins, Selectins, and G-protein coupled receptors have different roles. Cadherins are involved in homophilic cell-cell adhesion, Selectins mediate cell-cell binding in the immune system, and G-protein coupled receptors are involved in transmitting signals from a variety of stimuli outside a cell to its interior. However, the most important family of proteins that connects cells with the ECM, having alpha and beta subunits, are Integrins.