Anti-Haptoglobin/HP Antibody Picoband® Fluoro647 Conjugated

Haptoglobin (HP), is a protein that in humans is encoded by the HP gene. Haptoglobin, a plasma glycoprotein that binds free hemoglobin, has a tetrameric structure of 2 alpha and 2 beta polypeptides that are covalently associated by disulfide bonds. Haptoglobin is homologous to serine proteases of the chymotrypsinogen family. In the chimpanzee, there are 3 genes in the haptoglobin family (haptoglobin, HP; haptoglobin-related, HPR; and haptoglobin-primate, HPP), whereas only 2 genes exist in humans (HP and HPR) . There are similarities between the primary structures of the alpha chain and of light chains of gamma globulins. The alpha haptoglobin locus is on the long arm of chromosome 16, where its exact cytogenetic location is 16q22.2. A major function of haptoglobin is to bind hemoglobin (Hb) to form a stable Hp-Hb complex and thereby prevent Hb-induced oxidative tissue damage. Haptoglobin is an unusual secretory protein in that it is proteolytically processed in the endoplasmic reticulum and not in the Golgi. The human haptoglobin HP*2 allele contains a 1.7-kb intragenic duplication that arose after a unique nonhomologous recombination between the prototype HP*1 alleles.

As a result of hemolysis, hemoglobin is found to accumulate in the kidney and is secreted in the urine. Haptoglobin captures, and combines with free plasma hemoglobin to allow hepatic recycling of heme iron and to prevent kidney damage. Haptoglobin also acts as an Antimicrobial; Antioxidant, has antibacterial activity and plays a role in modulating many aspects of the acute phase response. Hemoglobin/haptoglobin complexes are rapidely cleared by the macrophage CD163 scavenger receptor expressed on the surface of liver Kupfer cells through an endocytic lysosomal degradation pathway. .

1. Asakawa, J., Kodaira, M., Nakamura, N., Satoh, C., Fujita, M. Chimerism in humans after intragenic recombination at the haptoglobin locus during early embryogenesis. Proc. Nat. Acad. Sci. 96: 10314-10319, 1999. 2. Bensi, G., Raugei, G., Klefenz, H., Cortese, R. Structure and expression of the human haptoglobin locus. EMBO J. 4: 119-126, 1985. 3. Bloom, G. E., Gerald, P. S., Reisman, L. E. Ring D chromosome: a second case associated with anomalous haptoglobin inheritance. Science 156: 1746-1748, 1967.