Bovine Lactadherin from Prolytix

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Overview of Bovine Lactadherin

Lactadherin is a widely distributed glycoprotein (~50 kDa) originally characterized due to its association with milk fat/lipid globule membranes. It is also known by other names such as PAS-6/7, bovine-associated mucoprotein, BA-46, P47, and MFG-E8.

Structural Hallmarks

Structural hallmarks of bovine lactadherin are the presence of two epidermal growth factor-like domains (with an Arg-Gly-Asp peptide motif in the second epidermal growth factor-like domain), and two C domains sharing homology with the discoidin family of lectin domains which includes the phospholipid-binding domains of blood clotting factors V and VIII (1).

Positively-charged residues in the second C domain are involved in the binding to phosphatidyl-L-serine (PS) on cell membranes. Hydrophobic aromatic residues stabilize the docking of PS with the second C domain. The second epidermal growth factor-like domain of lactadherin binds to integrins, like αvβ3, and promotes phagocytosis by macrophages.

Physiological and Pathological Roles

In vivo, lactadherin contributes to a variety of cellular interactions and plays an important role in many physiological and pathological processes including not only phagocytosis, but also atherosclerosis, angiogenesis, and protection against viruses (1). It also may function as a cell adhesion protein in the connection of smooth muscles to fibers in arteries.

Anticoagulant Properties

Lactadherin functions as an anticoagulant by blocking PS-containing membrane sites for blood coagulation proteins in a calcium-independent manner (2).

Comparison with Annexin V in Apoptotic Cell Detection

Studies comparing the dynamics of PS binding to lactadherin and annexin V, another PS-binding protein, demonstrate that lactadherin will bind to membranes that have a PS content below the threshold for annexin V binding and can detect apoptotic cells earlier than annexin V (3).

Thus, lactadherin is a highly sensitive probe for exposed phosphatidylserine on nucleated cells, activated platelets, and extracellular vesicles (1, 3, 4).

Available Products from Prolytix

Bovine Lactadherin (BLAC-1200)

• Purified from unpasteurized bovine milk.
• Purity assessed by SDS-PAGE is ≥95%.
• Custom formulations, modifications, and conjugations available.

Bovine Lactadherin-FITC Labeled (BLAC-FITC)

• AlexaFluor dyes
• Purified bovine lactadherin conjugated to FITC.
• Purity and fluorescence labeling confirmed by SDS-PAGE.
• Custom labeling options available, including:
  • PE
  • PAC-B
  • AlexaFluor dyes

About Prolytix

Prolytix has been providing customers with high-quality research reagents and custom collection devices since 1987. Learn more about these reagents and others such as their custom collection devices in Prolytix extensive product catalog or visit their supplier page.

Recent Publications Using Prolytix Bovine Lactadherin

• Drexhage LZ, Zhang S, Dupont M, et al. Apoptosis-mediated ADAM10 activation removes a mucin barrier promoting T cell efferocytosis. Nat Commun 15:541, 2024.
• Fager AM, et al. Emicizumab promotes factor Xa generation on endothelial cells. J Thromb Haemost 22:1605, 2024.
• Herzig MC, Christy BA, Montgomery RK, et al. Short-term assays for mesenchymal stromal cell immunosuppression of T-lymphocytes. Front Immunol 26;14:1225047, 2023.
• Botha J, Handberg A, and Simonsen JB. Lipid-based strategies used to identify extracellular vesicles in flow cytometry can be confounded by lipoproteins: Evaluations of annexin V, lactadherin, and detergent lysis. J Extracell Vesicles 11(4):e12200, 2022.
• Zhou Y, Cai W, Zhao Z, et al. Lactadherin promotes microvesicle clearance to prevent coagulopathy and improves survival of severe TBI mice. Blood 131:563, 2018.

References

(1) Kamińska A, Enguita FJ, and Stępień E. Lactadherin: An unappreciated haemostasis regulator and potential therapeutic agent. Vasc Pharmacol 101:21-28, 2018.
(2) Shi J and Gilbert GE. Lactadherin inhibits enzyme complexes of blood coagulation by competing for phospholipid binding sites. Blood 101:2628-2636, 2003.
(3) Shi J, Shi Y, Waehrens LN, et al. Lactadherin detects early phosphatidylserine exposure on immortalized leukemia cells undergoing programmed cell death. Cytometry A 69:1193-1201, 2006.
(4) Dasgupta SK, Guchhait P, and Thiagarajan P. Lactadherin binding and phosphatidylserine expression on cell surface-comparison with annexin A5. Transl Res 148:19-25, 2006.