User:Andrea Foote/Sandbox 1: Difference between revisions

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==Purine-rich element binding protein alpha==

== Introduction ==

'''Purine-rich element binding protein alpha (Purα)''' is a transcription factor with a molecular weight of ~35 kDa encoded by the PURA gene. It possesses ATP-independent dsDNA unwinding activity, and is known to bind sequence-specific purine-rich regions of ssDNA and ssRNA, recognizing GGN motifs. Purα is a member of the PUR family of proteins, which includes Purβ and two isoforms of Purγ. In its functional dimeric form Purα is known to repress expression of smooth muscle alpha actin (SMαA) encoded by the ''Acta2'' gene. It is also known to be involved in DNA replication and cell cycle regulation as well as mRNA translation. It plays a crucial role in nervous system development, and mutations in Purα have been implicated in two neurological diseases: PURA syndrome and Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) (see Disease section).<ref>PMID:26744780</ref>

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== Structure ==

[[Image:180429 proteopedia pura figures2.jpg|thumb|right|300px| A PUR domain is analogous to a left-handed handshake. PUR repeat I-II represented from [[5fgp]].]]

Purα functions as a dimer composed of two intramolecular domains and one intermolecular domain. The Purα monomer contains three semi-conserved repeated amino acid sequences, named in order from N->C: PUR repeats I, II, and III. These repeats fold to form two domains: <scene name='78/786627/5fgp_intro/8'>PUR repeats I and II</scene> associating to form the I-II domain or “intramolecular domain”, while <scene name='78/786627/5fgo_repeatiii/2'>PUR repeat III</scene> facilitates dimerization through association with a repeat III from a second Purα monomer or repeat III of Purβ. Each PUR repeat is connected by flexible linker regions. Each PUR repeat contains a beta-sheet composed of four beta-strands, followed by a single alpha-helix. While Purα is not yet officially classified by SCOP or CATH, its structure is that of an α+β protein.

Purα functions as a dimer composed of two intramolecular domains and one intermolecular domain. The Purα monomer contains three semi-conserved repeated amino acid sequences, named in order from N->C: PUR repeats I, II, and III. These repeats fold to form two domains: <scene name='78/786627/5fgp_intro/9'>PUR repeats I and II</scene> associating to form the I-II domain or “intramolecular domain”, while <scene name='78/786627/5fgo_repeatiii/2'>PUR repeat III</scene> facilitates dimerization through association with a repeat III from a second Purα monomer or repeat III of Purβ. Each PUR repeat is connected by flexible linker regions. Each PUR repeat contains a beta-sheet composed of four beta-strands, followed by a single alpha-helix. While Purα is not yet officially classified by SCOP or CATH, its structure is that of an α+β protein.

[[Image:180503 PurA Why2 comparison.jpg|thumb|right|300px| PUR domains are structurally similar to the fold in Whirly proteins. Left: PUR repeat I-II ([[5fgp]]), right: WHY2 ([[3n1k]]).]]

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 ==Purine-rich element binding protein alpha==
-<StructureSection load='5fgp' size='340' side='right' caption='''Drosophila Purα intramolecular domain (purple: PUR repeat I, orange: PUR repeat II) in complex with DNA (green). X-ray diffraction, 2Å resolution ([[5fgp]]).''' scene='78/786627/5fgp_intro/8'>
+<StructureSection load='5fgp' size='340' side='right' caption='''Drosophila Purα intramolecular domain (purple: PUR repeat I, orange: PUR repeat II) in complex with DNA (green). X-ray diffraction, 2Å resolution ([[5fgp]]).''' scene='78/786627/5fgp_intro/9'>
 == Introduction ==
 '''Purine-rich element binding protein alpha (Purα)'''  is a transcription factor with a molecular weight of ~35 kDa encoded by the PURA gene. It possesses ATP-independent dsDNA unwinding activity, and is known to bind sequence-specific purine-rich regions of ssDNA and ssRNA, recognizing GGN motifs. Purα is a member of the PUR family of proteins, which includes Purβ and two isoforms of Purγ. In its functional dimeric form Purα is known to repress expression of smooth muscle alpha actin (SMαA) encoded by the ''Acta2'' gene. It is also known to be involved in DNA replication and cell cycle regulation as well as mRNA translation. It plays a crucial role in nervous system development, and mutations in Purα have been implicated in two neurological diseases: PURA syndrome and Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) (see Disease section).<ref>PMID:26744780</ref>
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 == Structure ==
 [[Image:180429 proteopedia pura figures2.jpg|thumb|right|300px| A PUR domain is analogous to a left-handed handshake. PUR repeat I-II represented from [[5fgp]].]]
-Purα functions as a dimer composed of two intramolecular domains and one intermolecular domain. The Purα monomer contains three semi-conserved repeated amino acid sequences, named in order from N->C: PUR repeats I, II, and III. These repeats fold to form two domains: <scene name='78/786627/5fgp_intro/8'>PUR repeats I and II</scene> associating to form the I-II domain or “intramolecular domain”, while <scene name='78/786627/5fgo_repeatiii/2'>PUR repeat III</scene> facilitates dimerization through association with a repeat III from a second Purα monomer or repeat III of Purβ. Each PUR repeat is connected by flexible linker regions. Each PUR repeat contains a beta-sheet composed of four beta-strands, followed by a single alpha-helix. While Purα is not yet officially classified by SCOP or CATH, its structure is that of an α+β protein.
+Purα functions as a dimer composed of two intramolecular domains and one intermolecular domain. The Purα monomer contains three semi-conserved repeated amino acid sequences, named in order from N->C: PUR repeats I, II, and III. These repeats fold to form two domains: <scene name='78/786627/5fgp_intro/9'>PUR repeats I and II</scene> associating to form the I-II domain or “intramolecular domain”, while <scene name='78/786627/5fgo_repeatiii/2'>PUR repeat III</scene> facilitates dimerization through association with a repeat III from a second Purα monomer or repeat III of Purβ. Each PUR repeat is connected by flexible linker regions. Each PUR repeat contains a beta-sheet composed of four beta-strands, followed by a single alpha-helix. While Purα is not yet officially classified by SCOP or CATH, its structure is that of an α+β protein.
 [[Image:180503 PurA Why2 comparison.jpg|thumb|right|300px| PUR domains are structurally similar to the fold in Whirly proteins. Left: PUR repeat I-II ([[5fgp]]), right: WHY2 ([[3n1k]]).]]