The cells of the oviduct induce the sperm to mature, and mammalian sperm complete their development in the female oviducts. This maturation is called capacitation (the gaining of capacity).

TLS Online TPP Program

#Id: 1716

#Unit 4. Cell Communication and Cell Signaling

The serum half-life of IgE is quite short (only 2 to 3 days). However, when bound to its receptor on an innate immune cell, IgE is stable for weeks.

TLS Online TPP Program

#Id: 1717

#Unit 4. Cell Communication and Cell Signaling

IgE binds two different receptors, the high-affinity FcεRI, which is responsible for most of the symptoms we associate with allergy, and the lower-affinity FcεRII, which regulates the production of IgE by B cells, as well as its transport across cells.

TLS Online TPP Program

#Id: 1718

#Unit 4. Cell Communication and Cell Signaling

FcεRI, which binds IgE with an exceptionally high-affinity constant of 10^10 M^-1 .

TLS Online TPP Program

#Id: 1719

#Unit 4. Cell Communication and Cell Signaling

The other IgE receptor, designated FcεRII, or CD23, has a much lower affinity for IgE (Kd of 1 * 10 6 M -1 )

TLS Online TPP Program

#Id: 1720

#Unit 4. Cell Communication and Cell Signaling

Most cells express a tetrameric form of FcεRI, which includes an α and β chain and two identical disulfide-linked γ chains.

TLS Online TPP Program

#Id: 1721

#Unit 4. Cell Communication and Cell Signaling

Monocytes and platelets express an alternative form lacking the β chain.