SA node has Prepotential or pacemaker potential which is the gradual potential rise from the resting membrane potential to threshold  ( -40 mV) & this occur spontaneously.

TLS Online TPP Program

#Id: 7457

#Unit 5. Developmental Biology

TLS Online TPP Program

#Id: 7458

#Unit 5. Developmental Biology

The binding of ammonia to the sensor domain of DhkC leads to the activation of its histidine kinase activity and to the autophosphorylation of a DhkC histidine residue.

TLS Online TPP Program

#Id: 7459

#Unit 5. Developmental Biology

The phosphoryl group is transferred,  From histidine residue of DhkC  aspartate of DhkC histidine in phospho-transfer intermediate RdeA aspartate of RR of RegA

TLS Online TPP Program

#Id: 7460

#Unit 5. Developmental Biology

Ammonia inhibits PKA by indirectly activating cAMP hydrolysis via DhkC-RdeA mediated phosphorylation of RegA.

TLS Online TPP Program

#Id: 7461

#Unit 5. Developmental Biology

Binding of Spore differentiation factor 2 activates the histidine phosphatase activity of DhkA (histidine phosphatase A)

TLS Online TPP Program

#Id: 7462

#Unit 5. Developmental Biology

Histidine phosphatase activity of DhkA causes inactivation of RegA, the accumulation of cAMP and PKA activation, causes spore maturation.