Final answer:
Cadherins are the protein group that links cells together by recognizing and binding to receptors on other cells or the extracellular matrix, forming cell-cell junctions like desmosomes.
Step-by-step explanation:
The protein group that links cells together by recognizing and binding receptors or chemical groups on other cells or the extracellular matrix is Cadherins. These are glycoproteins that are especially important in forming adherens junctions such as desmosomes, acting as the 'glue' for cohesive tissues. Cadherins work in collaboration with other cellular components to ensure cells adhere to each other, maintaining structural integrity in organs and tissues that experience stretching forces like skin, heart, and muscles.
Integrins are another group of proteins that mediate the attachment between cells and the extracellular matrix but, unlike cadherins, they are more involved in attachment to the ECM rather than cell-to-cell adhesion. While selectins and actins play significant roles in various cell interactions and structures, such as blood clotting and the cytoskeleton, respectively, they do not directly link cells together.