The positional information needed to construct a limb has to function in a three-dimensional coordinate system:

Proximal-distal axis

Anterior-posterior axis

Dorsal-ventral axis

TLS Online TPP Program

#Id: 1724

#Unit 4. Cell Communication and Cell Signaling

CD23 binds not only to IgE, but also to the complement receptor CD21.

TLS Online TPP Program

#Id: 1725

#Unit 4. Cell Communication and Cell Signaling

Soluble CD23 binds to CD21 on the surface of IgE synthesizing B cells, IgE synthesis is increased.

TLS Online TPP Program

#Id: 1726

#Unit 4. Cell Communication and Cell Signaling

When membrane-bound CD23 binds to soluble IgE, further IgE synthesis is suppressed.

TLS Online TPP Program

#Id: 1727

#Unit 4. Cell Communication and Cell Signaling

FcεRIIB, bear immuno-receptor tyrosine inhibitory motifs Cross-linking of these receptors leads to inhibition, rather than to activation of cellular responses.

TLS Online TPP Program

#Id: 1728

#Unit 4. Cell Communication and Cell Signaling

If an allergen binds both IgG and IgE molecules, it will trigger signals through both Fc receptors. The inhibitory signal dominates.

TLS Online TPP Program

#Id: 1729

#Unit 4. Cell Communication and Cell Signaling

FcεRI pathways are phosphorylations, multiple phosphatases, such as SHPs, SHIPs, and PTEN, play an important role in dampening receptor signaling.