Characterization of CLA-1, a human homologue of rodent scavenger receptor BI, as a receptor for high density lipoprotein and apoptotic thymocytes

J Biol Chem. 1997 Jul 11;272(28):17551-7. doi: 10.1074/jbc.272.28.17551.

Abstract

Recently, a murine scavenger receptor type B class I (SR-BI) was identified that binds high density lipoprotein (HDL) and mediates the selective uptake of cholesterol esters. The human CD36 and LIMPII analogous-1 (CLA-1) receptor shows high sequence homology with SR-BI, but their functional relationship has not been determined. Transfected cells expressing CLA-1 bound HDL with a Kd of about 35 microg/ml, similar to the Kd for HDL binding to rodent SR-BI. This binding resulted in an intracellular accumulation of HDL-derived [3H]cholesterol esters without internalization or degradation of 125I-apolipoprotein. CLA-1 was strongly expressed in the adrenal gland and was also abundant in liver and testis, suggesting that CLA-1, like SR-BI, could play a role in the metabolism of HDL. However, CLA-1 was also expressed in monocytes and, like SR-BI, recognized modified forms of low density lipoproteins as well as native LDL and anionic phospholipids. These findings suggest that CLA-1 might have additional physiological functions. We found that CLA-1 recognizes apoptotic thymocytes. Our results demonstrate that CLA-1, a close structural homologue of SR-BI, is also functionally related to SR-BI and may play an important role as a "docking receptor" for HDL in connection with selective uptake of cholesterol esters. An additional role in recognition of damaged cells is suggested by these studies.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apoptosis*
  • Blotting, Western
  • CD36 Antigens / genetics
  • CD36 Antigens / metabolism*
  • Carrier Proteins*
  • Cell Line
  • Cholesterol Esters / metabolism
  • Humans
  • Ligands
  • Lipoproteins, HDL / metabolism*
  • Membrane Proteins*
  • Mice
  • RNA-Binding Proteins*
  • Receptors, Immunologic*
  • Receptors, Lipoprotein / metabolism*
  • Receptors, Scavenger
  • Scavenger Receptors, Class B
  • Thymus Gland / cytology*

Substances

  • CD36 Antigens
  • Carrier Proteins
  • Cholesterol Esters
  • Ligands
  • Lipoproteins, HDL
  • Membrane Proteins
  • RNA-Binding Proteins
  • Receptors, Immunologic
  • Receptors, Lipoprotein
  • Receptors, Scavenger
  • SCARB1 protein, human
  • Scarb1 protein, mouse
  • Scavenger Receptors, Class B
  • high density lipoprotein receptors
  • high density lipoprotein binding protein