The b subunit of RNA polymerase is implicated by two types of mutation. 

First, mutations in the rpoB gene can reduce termination at a rho-dependent site. 

Second, mutations in rpoB can restore the ability to terminate transcription at rho-dependent sites in rho mutant bacteria.

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#Unit 7. System Physiology – Animal

In early proximal convoluted tubule

sodium is reabsorbed by co-transport along with glucose, amino acids, & other solutes

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#Unit 7. System Physiology – Animal

Late proximal tubule reabsorbs primarily NaCl.

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#Unit 7. System Physiology – Animal

In late proximal convoluted tubule

High tubular fluid Cl− concentration is the driving

force for reabsorption

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#Unit 7. System Physiology – Animal

There are two components for Cl− reabsorption:

Transcellular

Paracellular

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#Unit 7. System Physiology – Animal

Function of the two exchangers is to transport NaCl from the lumen into the cell:

Na+-H+ exchanger

Cl−-formate− anion exchanger

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#Unit 7. System Physiology – Animal

The proximal tubule is an important site for secretion of organic acids and bases such as bile salts, oxalate, urate, and catecholamines.