Cysteine-rich secretory protein 3 is a ligand of alpha1B-glycoprotein in human plasma

TY - JOUR

T1 - Cysteine-rich secretory protein 3 is a ligand of alpha1B-glycoprotein in human plasma

AU - Udby, Lene

AU - Sørensen, Ole E

AU - Pass, Jesper

AU - Johnsen, Anders H

AU - Behrendt, Niels

AU - Borregaard, Niels

AU - Kjeldsen, Lars

PY - 2004/10/12

Y1 - 2004/10/12

N2 - Human cysteine-rich secretory protein 3 (CRISP-3; also known as SGP28) belongs to a family of closely related proteins found in mammals and reptiles. Some mammalian CRISPs are known to be involved in the process of reproduction, whereas some of the CRISPs from reptiles are neurotoxin-like substances found in lizard saliva or snake venom. Human CRISP-3 is present in exocrine secretions and in secretory granules of neutrophilic granulocytes and is believed to play a role in innate immunity. On the basis of the relatively high content of CRISP-3 in human plasma and the small size of the protein (28 kDa), we hypothesized that CRISP-3 in plasma was bound to another component. This was supported by size-exclusion chromatography and immunoprecipitation of plasma proteins. The binding partner was identified by mass spectrometry as alpha(1)B-glycoprotein (A1BG), which is a known plasma protein of unknown function and a member of the immunoglobulin superfamily. We demonstrate that CRISP-3 is a specific and high-affinity ligand of A1BG with a dissociation constant in the nanomolar range as evidenced by surface plasmon resonance. The A1BG-CRISP-3 complex is noncovalent with a 1:1 stoichiometry and is held together by strong electrostatic forces. Similar complexes have been described between toxins from snake venom and A1BG-like plasma proteins from opossum species. In these cases, complex formation inhibits the toxic effect of snake venom metalloproteinases or myotoxins and protects the animal from envenomation. We suggest that the A1BG-CRISP-3 complex displays a similar function in protecting the circulation from a potentially harmful effect of free CRISP-3.

AB - Human cysteine-rich secretory protein 3 (CRISP-3; also known as SGP28) belongs to a family of closely related proteins found in mammals and reptiles. Some mammalian CRISPs are known to be involved in the process of reproduction, whereas some of the CRISPs from reptiles are neurotoxin-like substances found in lizard saliva or snake venom. Human CRISP-3 is present in exocrine secretions and in secretory granules of neutrophilic granulocytes and is believed to play a role in innate immunity. On the basis of the relatively high content of CRISP-3 in human plasma and the small size of the protein (28 kDa), we hypothesized that CRISP-3 in plasma was bound to another component. This was supported by size-exclusion chromatography and immunoprecipitation of plasma proteins. The binding partner was identified by mass spectrometry as alpha(1)B-glycoprotein (A1BG), which is a known plasma protein of unknown function and a member of the immunoglobulin superfamily. We demonstrate that CRISP-3 is a specific and high-affinity ligand of A1BG with a dissociation constant in the nanomolar range as evidenced by surface plasmon resonance. The A1BG-CRISP-3 complex is noncovalent with a 1:1 stoichiometry and is held together by strong electrostatic forces. Similar complexes have been described between toxins from snake venom and A1BG-like plasma proteins from opossum species. In these cases, complex formation inhibits the toxic effect of snake venom metalloproteinases or myotoxins and protects the animal from envenomation. We suggest that the A1BG-CRISP-3 complex displays a similar function in protecting the circulation from a potentially harmful effect of free CRISP-3.

KW - Blood Proteins

KW - Chromatography

KW - Glycoproteins

KW - Glycosylation

KW - Humans

KW - Immunoglobulins

KW - Kinetics

KW - Ligands

KW - Molecular Weight

KW - Protein Binding

KW - Salivary Proteins and Peptides

KW - Seminal Plasma Proteins

KW - Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

KW - Surface Plasmon Resonance

KW - Titrimetry

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1021/bi048823e

DO - 10.1021/bi048823e

M3 - Journal article

C2 - 15461460

SN - 0006-2960

VL - 43

SP - 12877

EP - 12886

JO - Biochemistry

JF - Biochemistry

IS - 40

ER -