The protein encoded by this gene is a component of the innate immune system. CD14 exists in two forms. It is either anchored into the membrane by a a glycosylphosphatidylinositol tail (mCD14) or it appears in a soluble form (sCD14). Soluble CD14 appears either after shedding of mCD14 (48 KDa) or is directly secreted from intracellular vesicles (56 KDa).
CD14 takes its name from its inclusion in the cluster of differentiation group of cell surface marker proteins.
CD14 was the first described pattern recognition receptor.
Function
CD14 acts as a co-receptor (along with the Toll-like receptor TLR 4 and MD-2) for the detection of bacterial lipopolysaccharide (LPS). CD14 can only bind LPS in the presence of lipopolysaccharide-binding protein (LBP). Although LPS is considered it's main ligand CD14 also recognizes other pathogen associated molecular patterns.
Tissue distribution
CD14 is expressed mainly by macrophages and (at 10 times lesser extent) by neutrophil granulocytes. A soluble form sCD14 is secreted by the liver and monocytes and is sufficient in low concentrations to confer LPS-responsiveness to cells which otherwise do not express CD14.Differentiation
CD14+ are monocytes that can differentiate into a host of different cells. (A '+' sign refers to the presence of the CD14 protein on a cell. )One type of cell is the dendritic cell, where differentiation is encouraged by cytokines. Examples of cytokines that will cause dendritic cell differentiation includes GM-CSF and IL-4.
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Further reading
This article is licensed under the GNU Free Documentation License.
Last updated on Wednesday September 03, 2008 at 01:15:40 PDT (GMT -0700)
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