• Purity

  >95%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by the ability of the immobilized protein to support the adhesion of HeLa human cervical epithelial carcinoma cells. The ED    ₅₀ for this effect is 0.25-1.0 μg/mL.

• Source

  Mouse myeloma cell line, NS0-derived Gln22-His163, with a C-terminal 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  No results obtained: Gln22 predicted, sequencing might be blocked

• Predicted Molecular Mass

  16.3 kDa

• SDS-PAGE

  28-33 kDa, reducing conditions

Background: LAIR1

LAIR1 (leukocyte-associated Ig-like receptor-1, designated CD305) is an approximately 40 kDa type I transmembrane inhibitory glycoprotein belonging to the Ig superfamily (1-4). LAIR1 is a collagen-binding protein that is expressed in a differentiation- and activation-dependent manner on most immune cells, including T, B, NK and dendritic cells (DC), monocytes, CD34+ hematopoietic progenitors, most thymocytes, and selected granulocyte populations (2-7). Mature human LAIR1 is a 266 amino acid (aa) type I transmembrane protein that includes a 144 aa extracellular domain (ECD) with one collagen-binding C2-type Ig-like domain, and a 101 aa cytoplasmic domain with two ITIM motifs (2, 3, 8, 9). Of four potential human LAIR1 splice variants, LAIR1b has a 17 aa deletion within the ECD, but outside the Ig domain. LAIR1c differs from LAIR1b by one aa. LAIR1d has a 78 aa cytoplasmic truncation and lacks ITIM motifs. Human LAIR1 ECD shares<45% aa sequence identity with mouse, rat, bovine or canine LAIR1 ECD, but all are functional orthologs. Humans, but not rodents, also express the 152 aa secreted protein LAIR2, which shares 83% aa sequence identity with the LAIR1 ECD up to aa 140 and can block LAIR1 collagen binding (1, 2). A soluble form of LAIR1 found in plasma and urine also binds collagen (10).  Adhesion of LAIR1 to collagens in the extracellular matrix, transmembrane collagens expressed by tumor cells, or antibody-mediated crosslinking of LAIR1, inhibits signals relayed by ITAM-bearing receptors and some cytokine-mediated signals (6-8, 13).  Processes that are inhibited include B and T cell receptor-mediated activation, NK and T cell‑mediated cytotoxicity, and basophil degranulation (1-4, 8). LAIR1 is reduced or absent on chronic lymphocytic leukemia (CLL) B cells, and some B and DC cells in systemic lupus erythematosus (SLE). Its under‑expression potentially enhances CLL proliferation and SLE immune responses (7, 11, 12).

• References:

1. Meyaard, L. (2008) J. Leukoc. Biol. 83:799.

2. Meyaard, L. et al. (1997) Immunity 7:283.

3. Lebbink, R.J. et al. (2004) J. Immunol. 172:5535.

4. Ouyang, W. et al. (2003) Biochem. Biophys. Res. Commun. 310:1236.

5. Verbrugge, A. et al. (2006) J. Leukoc. Biol. 79:828.

6. Lebbink, R.J. et al. (2006) J. Exp. Med. 203:1419.

7. Bonaccorsi, I. et al. (2010) PLoS ONE 5:e15080.

8. Tang, X. et al. (2009) J. Immunol. 182:5446.

9. Brondijk, T.H.C. et al. (2010) Blood 115:1364.

10. Olde Nordkamp, M.J. et al. (2011) Arthritis Rheum. 63:3749.

11. Poggi, A. et al. (2008) Leukemia 22:980.

12. Colombo, B.M. et al. (2012) PLoS ONE 7:e31903.

13. Rygiel, T.P. et al. (2011) Mol. Immunol. 49(1-2):402.

• Long Name:

  Leukocyte-associated Ig-like Receptor 1

• Entrez Gene IDs:

  3903 (Human)

• Alternate Names:

  CD305 antigen; CD305; CD305leukocyte-associated Ig-like receptor 1; hLAIR1; LAIR1; LAIR-1; leukocyte-associated immunoglobulin-like receptor 1