Each DnaB–DnaC complex consists of six DnaC monomers bound to a hexamer of DnaB.

Note that the DnaB helicase cannot open double-stranded DNA; it can only unwind DNA that has already been opened, in this case by DnaA.

DnaB binding to single-stranded DNA is the signal to hydrolyze ATP and for release of DnaC.

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#Unit 6. System Physiology – Plant

Strigolactones act locally to repress axillary bud growth

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#Unit 6. System Physiology – Plant

Strigolactones are perceived by a protein complex containing an a-/b-fold hydrolase protein and an F-box protein (D14 and MAX2, respectively)

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#Unit 6. System Physiology – Plant

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#Unit 6. System Physiology – Plant

Long-distance transport of three hormones that regulate shoot branching: auxins, cytokinins, and strigolactones. Auxin is produced primarily in young expanding leaves and is transported basipetally by PIN1- mediated polar auxin transport. 

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#Unit 6. System Physiology – Plant

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#Unit 6. System Physiology – Plant

Brassinosteroids are synthesized from the plant sterol campesterol, which is similar in structure to cholesterol. Members of the cytochrome P450 monooxygenase (CYP) enzyme family that are associated with the ER catalyze most of the reactions in the brassinosteroid biosynthesis pathway.

Mevalonic acid serves as a precursor of the triterpenoid pathway and is condensed and transformed to 2,3-oxidosqualene which further undergoes modification to form major plant sterols like sitosterols and campesterols.