Serum and extracellular proteins

Serum and extracellular proteins represent a diverse group of proteins located outside the intracellular environment, primarily within the blood plasma and the interstitial spaces of tissues. This broad category encompasses a wide range of functional classes, including transport proteins like albumin, immune system components such as immunoglobulins and complement proteins, and structural elements of the extracellular matrix like collagen and fibronectin (1, 2). While the category itself is not a single therapeutic target, many individual proteins within this group are critical targets for drug intervention, such as clotting factors in hematology or cytokines in inflammatory diseases (3). Furthermore, the interaction of drugs with serum proteins, particularly albumin, is a fundamental determinant of a drug's pharmacokinetic profile, influencing its distribution, metabolism, and excretion (4). Dysregulation of these proteins is central to numerous pathologies, including cardiovascular disorders, cancer metastasis, and systemic inflammation, making them vital both as therapeutic targets and as diagnostic biomarkers (5). Because this term refers to a vast collection of distinct molecular entities rather than a specific receptor or enzyme, it is classified as a broad grouping rather than a singular therapeutic target.

Other names

Plasma proteinsSecreted proteinsExtracellular matrix proteinsCirculating proteinsExoproteins

Drugs targeting specific proteins within this category act through various mechanisms including enzyme inhibition (e.g., thrombin inhibitors), ligand neutralization (e.g., anti-cytokine antibodies), or structural modification of the extracellular matrix. Additionally, many drugs non-covalently bind to serum proteins like albumin, which significantly influences their pharmacokinetics and free fraction in the blood.