Haptoglobin-related protein is a high-affinity hemoglobin-binding plasma protein
- 15 October 2006
- journal article
- Published by American Society of Hematology in Blood
- Vol. 108 (8), 2846-2849
- https://doi.org/10.1182/blood-2006-05-022327
Abstract
Haptoglobin-related protein (Hpr) is a primate-specific plasma protein associated with apolipoprotein L-I (apoL-I)-containing high-density lipoprotein (HDL) particles shown to be a part of the innate immune defense. Despite the assumption hitherto that Hpr does not bind to hemoglobin, the present study revealed that recombinant Hpr binds hemoglobin as efficiently as haptoglobin (Hp). However, in contrast to Hp, Hpr did not promote any high-affinity binding to the scavenger receptor CD163. Binding of hemoglobin to circulating native Hpr incorporated into the HDL fraction was indicated by hemoglobin-affinity precipitation of plasma Hpr together with apoL-I. In conclusion, plasma has 2 high-affinity hemoglobin-binding haptoglobins instead of one, but only Hp-hemoglobin complexes are efficiently recognized by CD163. Circulating Hpr-bound hemoglobin should therefore be taken into consideration when measuring “free” plasma hemoglobin. Furthermore, Hpr-bound hemoglobin might contribute to the biologic activity of the circulating apoL-I/Hpr-containing HDL particles.Keywords
This publication has 20 references indexed in Scilit:
- Human High Density Lipoproteins Are Platforms for the Assembly of Multi-component Innate Immune ComplexesJournal of Biological Chemistry, 2005
- Apolipoprotein L-I Promotes Trypanosome Lysis by Forming Pores in Lysosomal MembranesScience, 2005
- Apolipoprotein L-I is the trypanosome lytic factor of human serumNature, 2003
- Enhanced splenomegaly and severe liver inflammation in haptoglobin/hemopexin double-null mice after acute hemolysisBlood, 2002
- Haptoglobin-related Protein Mediates Trypanosome Lytic Factor Binding to TrypanosomesJournal of Biological Chemistry, 2001
- Identification of the haemoglobin scavenger receptorNature, 2001
- Characterization of a Novel Trypanosome Lytic Factor from Human SerumInfection and Immunity, 1999
- Increased Susceptibility in Hp Knockout Mice During Acute HemolysisBlood, 1998
- Characterization of the Human Serum Trypanosome Toxin, Haptoglobin-related ProteinPublished by Elsevier ,1998
- Killing of Trypanosomes by the Human Haptoglobin-Related ProteinScience, 1995