Transitional B cells bound for a follicular fate undergo positive and negative selection in the spleen.

TLS Online TPP Program

#Id: 9856

#Unit 6. System Physiology – Plant

Mougeotia appears to have evolved the ability to exploit red light as a signal to induce a response (chloroplast movement) that is typically mediated by blue light.

TLS Online TPP Program

#Id: 9857

#Unit 6. System Physiology – Plant

phot1 is the primary phototropic receptor mediates phototropism in response to low and high fluence rates of blue light. 

phot2 mediates phototropism in response to high light intensities

TLS Online TPP Program

#Id: 9858

#Unit 6. System Physiology – Plant

Phototropin receptors are associated with the plasma membrane, where they function as light-activated serine/threonine kinases.

TLS Online TPP Program

#Id: 9859

#Unit 6. System Physiology – Plant

Phototropin contains two light-sensing LIGHT-OXYGEN-VOLTAGE (LOV) domains, LOV1 and LOV2, each binding a chromophore flavin mononucleotide (FMN).

TLS Online TPP Program

#Id: 9860

#Unit 6. System Physiology – Plant

In the dark, the maximum absorption of the FMN chromophore is around 450 nm. 

Blue light induces the formation of a covalent bond between FMN and a cysteine residue, shifting the absorption maximum to 390 nm via a LOV660 intermediate form. The reaction is reversible in darkness.

TLS Online TPP Program

#Id: 9861

#Unit 6. System Physiology – Plant

LOV2 domain is essential for blue light–induced kinase activation and autophosphorylation of the phototropin photoreceptor.