View source for 2ipz

[[Image:2ipz.gif|left|200px]]

 {{Structure
|PDB= 2ipz |SIZE=350|CAPTION= <scene name='initialview01'>2ipz</scene>, resolution 1.35&Aring;
|SITE= 
|LIGAND= <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene> and <scene name='pdbligand=IPA:ISOPROPYL ALCOHOL'>IPA</scene>
|ACTIVITY= 
|GENE= GCN4 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 Saccharomyces cerevisiae])
}}

'''A Parallel Coiled-Coil Tetramer with Offset Helices'''


==Overview==
Specific helix-helix interactions are fundamental in assembling the native state of proteins and in protein-protein interfaces. Coiled coils afford a unique model system for elucidating principles of molecular recognition between alpha helices. The coiled-coil fold is specified by a characteristic seven amino acid repeat containing hydrophobic residues at the first (a) and fourth (d) positions. Nonpolar side chains spaced three and four residues apart are referred to as the 3-4 hydrophobic repeat. The presence of apolar amino acids at the e or g positions (corresponding to a 3-3-1 hydrophobic repeat) can provide new possibilities for close-packing of alpha-helices that includes examples such as the lac repressor tetramerization domain. Here we demonstrate that an unprecedented coiled-coil interface results from replacement of three charged residues at the e positions in the dimeric GCN4 leucine zipper by nonpolar valine side chains. Equilibrium circular dichroism and analytical ultracentrifugation studies indicate that the valine-containing mutant forms a discrete alpha-helical tetramer with a significantly higher stability than the parent leucine-zipper molecule. The 1.35 A resolution crystal structure of the tetramer reveals a parallel four-stranded coiled coil with a three-residue interhelical offset. The local packing geometry of the three hydrophobic positions in the tetramer conformation is completely different from that seen in classical tetrameric structures yet bears resemblance to that in three-stranded coiled coils. These studies demonstrate that distinct van der Waals interactions beyond the a and d side chains can generate a diverse set of helix-helix interfaces and three-dimensional supercoil structures.

==About this Structure==
2IPZ is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IPZ OCA]. 

==Reference==
A parallel coiled-coil tetramer with offset helices., Liu J, Deng Y, Zheng Q, Cheng CS, Kallenbach NR, Lu M, Biochemistry. 2006 Dec 26;45(51):15224-31. Epub 2006 Nov 29. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17176044 17176044]
[[Category: Saccharomyces cerevisiae]]
[[Category: Single protein]]
[[Category: Liu, J.]]
[[Category: Lu, M.]]
[[Category: GOL]]
[[Category: IPA]]
[[Category: coiled coil]]
[[Category: parallel tetramer]]
[[Category: protein design]]
[[Category: protein structure]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 17:32:15 2008''