User:Andrea Foote/Sandbox 1: Difference between revisions

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== Function ==

High-affinity nucleic acid-binding function is dependent on Purα dimerization. Purα forms homodimers in addition to heterodimers with Purβ. PurA is known to repress various genes including

Purα binds to single stranded purine-rich regions of DNA or RNA. In particular, Purα (and Purβ) are known to bind the purine-rich tract containing an MCAT enhancer motif in the 5’ region of the sense strand of the smooth muscle alpha actin gene (''Acta2''). Purα functions as a repressor at both transcriptional and translational levels. At the level of transcription Purα (and Purβ) act in concert with Y-box-binding protein 1 (YB-1 in humans or MSY1 in mice) which binds the antisense pyrimidine-rich strand, together acting to repress ''Acta2'' expression. At the level of translation Purα, Purβ and MSY-1 (YB-1 in humans) have been shown to bind a region in exon 3 of ''Acta2'' mRNA that is structurally similar to the MCAT (AGGAATG) enhancer element and prevent transcription in fibroblasts.<ref>PMID:10608902</ref>

<scene name='78/786627/5fgp_57and145/1'>Two aromatic residues spatially conserved on PUR repeats I and II</scene>, Y57 (repeat I) and F145 (repeat II), located on the solvent-exposed surface of the beta-sheets, contribute to the DNA unwinding activity of Purα through base stacking interactions with DNA bases.<ref>PMID:26744780</ref> PUR repeat III also has an aromatic residue at this location (Y219) that could undergo base-stacking interactions with DNA, however Weber, et al. observed negligible unwinding activity in this repeat.<ref>PMID:26744780</ref> Furthermore, repeat III ~~was shown~~ to bind ~~DNA~~ with significantly less affinity than repeat I-II.

High-affinity nucleic acid-binding function is dependent on Purα dimerization. Purα forms homodimers in addition to heterodimers with Purβ. PurA is known to repress various genes including SMαA.

<scene name='78/786627/5fgp_57and145/1'>Two aromatic residues spatially conserved on PUR repeats I and II</scene>, Y57 (repeat I) and F145 (repeat II), located on the solvent-exposed surface of the beta-sheets, contribute to the DNA unwinding activity of Purα through base stacking interactions with DNA bases.<ref>PMID:26744780</ref> PUR repeat III also has an aromatic residue at this location (Y219) that could undergo base-stacking interactions with DNA, however Weber, et al. observed negligible unwinding activity in this repeat.<ref>PMID:26744780</ref> Furthermore, this group found repeat III to bind ssDNA with significantly less (~30-fold less) affinity than repeat I-II.

== Development ==

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*[[3NM7]] (Apo. ''Borrelia b.'' Note: the ''Borrelia'' homolog of Purα contains only one PUR repeat)<ref>PMID:20976240</ref>

*[[3N8B]] (Apo. ''Borrelia b.'' Note: the ''Borrelia'' homolog of Purα contains only one PUR repeat)<ref>PMID:20976240</ref>

== Additional Resources ==

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JSmol in Proteopedia <ref>DOI 10.1002/ijch.201300024</ref>

This page was created using JSmol in Proteopedia <ref>DOI 10.1002/ijch.201300024</ref>

== References ==

@@ Line 16: / Line 16: @@
 == Function ==
-High-affinity nucleic acid-binding function is dependent on Purα dimerization. Purα forms homodimers in addition to heterodimers with Purβ. PurA is known to repress various genes including
+Purα binds to single stranded purine-rich regions of DNA or RNA. In particular, Purα (and Purβ) are known to bind the purine-rich tract containing an MCAT enhancer motif in the 5’ region of the sense strand of the smooth muscle alpha actin gene (''Acta2''). Purα functions as a repressor at both transcriptional and translational levels. At the level of transcription Purα (and Purβ) act in concert with Y-box-binding protein 1 (YB-1 in humans or MSY1 in mice) which binds the antisense pyrimidine-rich strand, together acting to repress ''Acta2'' expression. At the level of translation Purα, Purβ and MSY-1 (YB-1 in humans) have been shown to bind a region in exon 3 of ''Acta2'' mRNA that is structurally similar to the MCAT (AGGAATG) enhancer element and prevent transcription in fibroblasts.<ref>PMID:10608902</ref>
-<scene name='78/786627/5fgp_57and145/1'>Two aromatic residues spatially conserved on PUR repeats I and II</scene>, Y57 (repeat I) and F145 (repeat II), located on the solvent-exposed surface of the beta-sheets, contribute to the DNA unwinding activity of Purα through base stacking interactions with DNA bases.<ref>PMID:26744780</ref> PUR repeat III also has an aromatic residue at this location (Y219) that could undergo base-stacking interactions with DNA, however Weber, et al. observed negligible unwinding activity in this repeat.<ref>PMID:26744780</ref> Furthermore, repeat III was shown to bind DNA with significantly less affinity than repeat I-II.
+High-affinity nucleic acid-binding function is dependent on Purα dimerization. Purα forms homodimers in addition to heterodimers with Purβ. PurA is known to repress various genes including SMαA.
+<scene name='78/786627/5fgp_57and145/1'>Two aromatic residues spatially conserved on PUR repeats I and II</scene>, Y57 (repeat I) and F145 (repeat II), located on the solvent-exposed surface of the beta-sheets, contribute to the DNA unwinding activity of Purα through base stacking interactions with DNA bases.<ref>PMID:26744780</ref> PUR repeat III also has an aromatic residue at this location (Y219) that could undergo base-stacking interactions with DNA, however Weber, et al. observed negligible unwinding activity in this repeat.<ref>PMID:26744780</ref> Furthermore, this group found repeat III to bind ssDNA with significantly less (~30-fold less) affinity than repeat I-II.
 == Development ==
@@ Line 44: / Line 47: @@
 *[[3NM7]] (Apo. ''Borrelia b.'' Note: the ''Borrelia'' homolog of Purα contains only one PUR repeat)<ref>PMID:20976240</ref>
 *[[3N8B]] (Apo. ''Borrelia b.'' Note: the ''Borrelia'' homolog of Purα contains only one PUR repeat)<ref>PMID:20976240</ref>
 == Additional Resources ==
@@ Line 50: / Line 52: @@
-JSmol in Proteopedia <ref>DOI 10.1002/ijch.201300024</ref>
+This page was created using JSmol in Proteopedia <ref>DOI 10.1002/ijch.201300024</ref>
 == References ==
 <references/>