Final answer:
Cadherins are cell-surface receptors comprised of large extracellular domains, a single transmembrane segment, and small intracellular domains, critical for cell-cell adhesion and intercellular communication.
Step-by-step explanation:
Cadherins are cell-surface receptors that play a critical role in cell-cell adhesion, which is fundamental for the formation of complex multicellular structures. These proteins are typically composed of three main parts: large extracellular domains, a single transmembrane segment, and small intracellular domains. The extracellular domains are involved in binding with cadherins of neighboring cells, facilitating the formation of adherens junctions (like desmosomes) that function as the 'glue' which binds cells to form cohesive tissues. The intracellular domains interact with the cytoplasmic proteins and link to the cytoskeleton inside the cell, which provides structural support and transmits signals.
The transmembrane segment is a hydrophobic region that ensures the cadherin receptor is anchored in the cell's plasma membrane. The functionality of these receptors is crucial because it allows the cells to adhere together and communicate, maintaining the structural integrity of tissues and facilitating intercellular signaling.