Practice Questions

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#Question id: 5670

Embryonic stem cells can be induced in the laboratory to differentiate into muscle, nerve, pancreatic, and other specialized cell types. It has recently become possible to trigger the dedifferentiation of somatic cells back into pluripotent cells (so-called induced pluripotent stem cells or iPS cells) by artificially enhancing the production of a relatively small number of key transcriptional factors known to be required for maintenance of pluripotency. Examples of such transcription factors are OCT4 and NANOG. The production of OCT4 and NANOG (and other key regulatory proteins) is stimulated by a transcription factor known as FOXP1, a member of the Forkhead family of DNA-binding proteins. There are two isoforms of FOXP1.

Which of the following statement regarding to FOXP1 is incorrect?

#Unit 5. Developmental Biology

The protein encoded by the exon 18b–carrying mRNA is called FOXP1-ES: this activates genes (OCT4, NANOG, etc.) that promote dedifferentiation, and thus stimulates iPS cell formation.
In the exon 18a–containing form encodes FOXP1 itself, and this has the opposite effect: it fails to stimulate expression of OCT4 and NANOG and instead actives genes that promote differentiation.
FOXP1 binds to DNA via a domain known as a Winged helix, which recognizes a particular DNA sequence.
The switch from exon 18a to exon 18b substitutes 3 residues in the Winged helix region of the protein including six amino acids that are known to contact DNA.