What is the primary component of the extracellular matrix?

The primary component of the extracellular matrix (ECM) is collagen, which plays a crucial role in providing structural support and strength to tissues. Collagen consists of several different types, each serving specific functions depending on the tissue type. It forms fibrous networks that help maintain the integrity of connective tissues such as cartilage, bone, and skin. This protein not only supports cell adhesion but also influences cell behavior, including proliferation and differentiation, making it essential in tissue development and repair.

The other proteins mentioned, such as elastin, keratin, and fibronectin, have important roles within the ECM as well but do not serve as the primary structural protein. Elastin contributes to the elasticity and resilience of tissues, keratin is a structural protein found in epithelial tissues, and fibronectin functions primarily in cell adhesion and migration. While they are all components of the ECM, collagen's predominant role in structural support distinguishes it as the primary component.