Sandbox Reserved 829: Difference between revisions
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The homeodomain protein folds into three α-helices, with helices 1 and 2 antiparallel to each other and perpendicular to helix 3, and a flexible N-terminal arm. | The homeodomain protein folds into three α-helices, with helices 1 and 2 antiparallel to each other and perpendicular to helix 3, and a flexible N-terminal arm. | ||
Helices 2 and 3 form a helix-turn-helix type motif. Indeed this tertiary structure motif consists of two α-helices and a short extended amino acids chain between them. The more carboxyl-terminal helix can fit into the major groove of DNA. | Helices 2 and 3 form a helix-turn-helix type motif. [http://en.wikipedia.org/wiki/Helix-turn-helix Wikipedia] | ||
Indeed this tertiary structure motif consists of two α-helices and a short extended amino acids chain between them. The more carboxyl-terminal helix can fit into the major groove of DNA. | |||
That is why, helix 3 (also known as the recognition helix) interacts with the the major groove of the DNA. | That is why, helix 3 (also known as the recognition helix) interacts with the the major groove of the DNA. | ||
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In pancreatic δ-cells, PDX-1 interacts with PBX1 and PREP1 corresponding respectively to PBC and MEIS proteins. These proteins belong to the three amino acids loop extension (TALE) family of homeodomains. By interacting with these proteins, PDX-1 can regulate the somatostatin promoter. Interaction with the TALE proteins is mediated through a conserved pentapeptide motif, FPWMK, located at the 10 residues of the N-terminal of the homeodomain. <ref>PMID : 11279116</ref> | In pancreatic δ-cells, PDX-1 interacts with PBX1 and PREP1 corresponding respectively to PBC and MEIS proteins. These proteins belong to the three amino acids loop extension (TALE) family of homeodomains. By interacting with these proteins, PDX-1 can regulate the somatostatin promoter. Interaction with the TALE proteins is mediated through a conserved pentapeptide motif, FPWMK, located at the 10 residues of the N-terminal of the homeodomain. <ref>PMID : 11279116</ref> | ||
In neural cells, PDX-1 utilizes a different binding site on the somatostatin promoter than in δ-cells, suggesting a distinct protein complex. PDX-1 interacts also with the basic helix-loop-helix (bHLH) factor E47/NeuroD. | In neural cells, PDX-1 utilizes a different binding site on the somatostatin promoter than in δ-cells, suggesting a distinct protein complex. PDX-1 interacts also with the basic helix-loop-helix (bHLH: [http://en.wikipedia.org/wiki/Basic_helix-loop-helix Wikipedia]) factor E47/NeuroD. | ||
In pancreatic acinar cells, PDX-1 interacts with Pbx1b and Mrg1 to regulate the elastase I gene. | In pancreatic acinar cells, PDX-1 interacts with Pbx1b and Mrg1 to regulate the elastase I gene. | ||
