Auxin-induced proton extrusion acidifies the cell wall and increases cell extension

Auxin increase the rate of proton extrusion (wall acidification), and the kinetics of proton extrusion should closely match those of auxin-induced growth.

TLS Online TPP Program

#Id: 9061

#Unit 4. Cell Communication and Cell Signaling

The GPK in skeletal muscle is a huge protein with multiple subunits:

Kinase subunit contains the catalytic activity that activates GP 

Regulatory subunits is the ubiquitous protein calmodulin

TLS Online TPP Program

#Id: 9062

#Unit 4. Cell Communication and Cell Signaling

GPK enzyme activity is increased either by phosphorylation of these two regulatory subunits by PKA or by Ca+2 binding to the calmodulin subunit; maximal activity requires both.

TLS Online TPP Program

#Id: 9063

#Unit 4. Cell Communication and Cell Signaling

Phosphorylation of PKA at threonine-197 leads to conformational change in the activation loop, that promotes binding of both ATP and its substrate proteins.

PKA can autophosphorylate itself on T197

TLS Online TPP Program

#Id: 9064

#Unit 4. Cell Communication and Cell Signaling

The activities of GPK and GP are inhibited by a phosphatase called phosphoprotein phosphatase.

TLS Online TPP Program

#Id: 9065

#Unit 4. Cell Communication and Cell Signaling

The promoter or enhancer segments of all genes regulated by PKA contain a cis-acting DNA sequence, the cAMP-response element (CRE), which

contains the highly conserved nucleotide sequence,

5'-TGACGTCA-3'.

TLS Online TPP Program

#Id: 9066

#Unit 4. Cell Communication and Cell Signaling

In nucleus PKA phosphorylate serine-133 on a transcription factor called CREbinding (CREB) protein