CD327 Siglec6 (sialic acid binding Ig-like lectin 6), OB-BP1, CD33L, CD33L1, CDw327
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
B Cell
Placenta
Spleen
Small intestine
Syncytiotrophoblast
Cytotrophoblast
49 / 49

Expression
CD327 is expressed by cyto- and syncytiotrophoblastic cells of placenta and B cells in the spleen and small intestine.  Expression is found at lower levels in neutrophils, granulocytes,
trophoblasts, and peripheral blood leukocytes (predominantly B cells).

Structure
MOLECULAR FAMILY NAME: Belongs to the immunoglobulin gene family.

CD327 is a single-pass type-1 427 aa lectin glycoprotein. It contains a 15 aa signal sequence, a 321 aa extracellular domain which contains 2 Ig-like C-type domains, a N-terminal Ig-like V-type domain and 6 potential N-linked glycosylation sites, 21 aa transmembrane domain and a 85 aa intracellular cytoplasmic domain which contains an immunoregulatory tyrosine based inhibitory motif (ITIM) and a signaling lymphocyte activating molecule (SLAM)-like motif that acts as a docking site for SLAM-associated protein (SAP). 
  
MOLECULAR MASS

POST-TRANSCRIPTIONAL MODIFICATION

Alternative splicing yields 2 different isoforms.  The isoforms include the membrane-bound form and a soluble form which lacks most of the cytoplasmic amino acids.

POST-TRANSLATIONAL MODIFICATION

CD327 has 6 potential N-linked glycosylation sites.  This  ITIM motif is involved in modulation of cellular responses.  The phosphorylated ITIM motif can bind the SH2 domain of several SH-2 containing phosphatases. 


Ligands
LIGANDS AND MOLECULE ASSOCIATED WITH CD327

CD327 recognizes Neu5Aca2-6GalNCAca (sialyl-Tn) motifs.  Unrelated to its sialic acid-binding activity, CD327 binds to the protein core of leptin with moderate affinity. 

Function
Molecules belonging to the Ig superfamily function as mediators of cell-cell interactions.  The sialoadhesin family, a group of sialic acid-binding proteins, is a subgroup of the Ig superfamily.  CD327, as a member of the Sigelec family, is a adhesion molecule and is predicted to mediate cell-cell recognition events between specific cell populations in the placenta, spleen and small intestine.  CD327 binds sialic acids at the cell surface and has been shown to specifically bind to leptin.  The sialic acid recognition site may be masked by cis interactions with sialic acids on the same cell surface.  The presence of signaling motifs in the cytoplasmic tail of the membrane-bound form of CD327 indicates a role in signal transduction.  The role of CD327 in leptin physiology is unknown, but it may be important during embryogenesis given that cyto- and syncytiotrophoblastic cells strongly express CD327 and leptin.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD327 IN INTACT ANIMAL: No information.










Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD327: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD327: No information.

ADDITIONAL INSIGHTS

For further information see Patel,N. et al (1999) J. Biol. Chem. 274: 22729-22738.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 946O43699
Antibodies

Revised June 25, 2008


Contact us: Webmaster |  509-335-9515 | Accessibility | Copyright | Policies
College of Veterinary Medicine Washington State University, Pullman, WA, 99164-7010 USA
Copyright 1995-2003 Washington State University