GlyCAM-1 Sgp50
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Lineage Restricted Molecule
Glycoprotein
Lymph Node
Endothelial Cell
45 / 55

Expression
GlyCAM-1, the glycosylation-dependent cell adhesion molecule 1, is expressed on the peripheral and mesenteric lymph node, high endothelial venules (HEVs), the lactating mammary gland, and unknown cells in the lung.  Expression has also been reported in HEV-like vessels at sites of chronic inflammation.  GlyCAM-1 is a secreted molecule and is detectable in blood and milk.

Structure
GlyCAM-1 is a heavily O-glycosylated soluble secreted glycoprotein. It is comprised of 2 segments within the extracellular region with 23-44 residues and 74-103 residues.  They contain a high proportion of ~50% serine- and threonine-residues and are likely to possess a mucin-like structure.  The N-terminus of the mature polypeptide has been established by protein sequencing.

MOLECULAR MASS
Cell Type Unreduced Reduced
50 kDa 50 kDa



Ligands
CD62L binds to carbohydrate structures present in some glycoforms of GlyCAM-1 expressed by HEVs.  The extract ligand has yet to be identified but binding requires sialylation, sulfation and probably fucosylation of GlyCAM-1 carbohydrates.  Notably, O-linked carbohydrates of GlyCAM-1 from the lymph node HEV contain sulfated forms of sialylated Lewis x (sLe x, Siaa2 ->3Galb1 ->4(Fuca 1 ->3)GlcNac), which contains all 3 groups.  In contrast, milk GlyCAM-1, which does not bind CD62L, is not sulfated.

Function
The identification of GlyCAM-1 as a secreted molecule suggests that it may modulate CD62L-mediated adhesion.  Consistent with an inhibitory role expression of GlyCAM-1 in the draining lymph node is dramatically decreased following antigen priming.  Soluble GlyCAM-1 can induce, via an interaction with cell surface CD62L, rapid activation of b2 CD18 integrins on na├»ve T cells.

Comments


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
MouseA41908Q02596M93428
RatA47167Q04807L08100
Antibodies

Revised June 25, 2008


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