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#gene activity

2 public questions tagged with this topic.

Eukaryotes gene regulation

Deletion construct showing >100% activity suggests presence of:

Promoter deletion analysis uses reporter fusions to map cis-elements. Wild-type promoter driving luciferase set as 100% activity. Progressive 5' deletions may reduce activity if activator site removed, indicating positive element. Unexpected increase above 100% suggests removed fragment contained repressive sequence or competing site, unmasking strong enhancer in retained portion. In GAL analyses, deleting Mig1 binding sites elevated expression in glucose while retaining UASG produced hyperactive constructs. Therefore constructs exceeding wild-type infer presence of enhancer module now freed from inhibitory context or repositioned closer to TATA box boosting transcription beyond normal constraints observed experimentally.

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 7: Promoter Deletion Analysis – Interpreting Enhancer Activity

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Gene Tar getting

In Cre-Off (DO) vectors, the gene is active before recombination and:

Cre-Off or double floxed inverted open reading frame systems express gene constitutively before recombination. Coding sequence flanked by incompatible lox sites in forward orientation remains active under promoter. Cre mediated inversion using opposite orientation loxP or lox2272 flips gene into antisense orientation, often followed by excision locking orientation, extinguishing transcription or producing non-functional transcript. Therefore activity before Cre allows labeling or function, after Cre signal terminates. This inversion dependent off switch enables Cre mediated silencing in specific neurons for circuit mapping.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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