The crystal packing shows a discrete tetramer water cluster.
Hong-Xia Cui, Yan-Chao Wang 2012, 'Discrete water clusters in tetra-μ-cyanido-tetracyanidobis(1,4,7-triisopropyl-1,4,7-triazacyclononane)dicopper(II)dinickel(II)tetrahydrate', Acta Crystallographica Section Ehttp://scripts.iucr.org/cgi-bin/paper?S1600536812024282. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
A tetramer library consisting of 256 tetramers covers all possible combinations of 4 base pairs.
Zhiqiang Zhang, Duo Li, Huarong Xu, Ying Xin, Tingting Zhang, Lixia Ma, Xin Wang,Zhilong Chen, Zhiying Zhang 2013, 'A simple and efficient method for assembling TALE protein based on plasmid library.',PLoS ONEhttp://europepmc.org/articles/PMC3688977?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Of these, a tetramer consisting of dimers represents the active unit.
Sandra Gemmecker, Patrick Schaub, Julian Koschmieder, Anton Brausemann, Friedel Drepper,Marta Rodriguez-Franco, Sandro Ghisla, Bettina Warscheid, Oliver Einsle, Peter Beyer 2015, 'Phytoene Desaturase from Oryza sativa: Oligomeric Assembly, Membrane Association andPreliminary 3D-Analysis', PLOS ONE10.1371/journal.pone.0131717. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Myoglobin was chosen due to the resemblance to each hemoglobin tetramer.
Katia Cecília de Souza Figueiredo, Wilbert van de Ven, Matthias Wessling, Tito LívioMoitinho Alves, Cristiano Piacsek Borges 2015, 'Immobilization of myoglobin in sodium alginate composite membranes', Polímeroshttp://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-14282015000300005&lng=en&tlng=en. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The tetramer binding sites are comprised of two dimer-binding sites repeated in tandem.
Bangalore K. Sathyanarayana, Peng Li, Jian-Xin Lin, Warren J. Leonard, Byungkook Lee 2016, 'Molecular Models of STAT5A Tetramers Complexed to DNA Predict Relative Genome-WideFrequencies of the Spacing between the Two Dimer Binding Motifs of the Tetramer BindingSites', PLOS ONE10.1371/journal.pone.0160339. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Tetramer disruption invariably abolishes restriction but has varied effects on in vitro triphosphohydrolase activity.
Laurence H Arnold, Harriet C T Groom, Simone Kunzelmann, David Schwefel, Sarah J Caswell,Paula Ordonez, Melanie C Mann, Sabrina Rueschenbaum, David C Goldstone, Simon Pennell,Steven A Howell, Jonathan P Stoye, Michelle Webb, Ian A Taylor, Kate N Bishop 2015, 'Phospho-dependent Regulation of SAMHD1 Oligomerisation Couples Catalysis and Restriction.',PLoS Pathogenshttp://europepmc.org/articles/PMC4592219?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Owing to interactions at the tetramer interface, the observed tetramer can be described as a dimer of dimers.
Carl eDiehl, Magdalena eWisniewska, Inga-Maria eFrick, Werner eStreicher, Lars eBjörck,Johan eMalmström, Mats eWikström 2016, 'Structure and interactions of a dimeric variant of sHIP, a novel virulence determinantof Streptococcus pyogenes', Frontiers in Microbiologyhttp://journal.frontiersin.org/Journal/10.3389/fmicb.2016.00095/full. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
There are a few that are octamers, with the eight subunits arranged as a tetramer of dimers.
Farhad Karbassi, Veronica Quiros, Vijay Pancholi, Mary J Kornblatt 2010, 'Dissociation of the octameric enolase from S. pyogenes--one interface stabilizes another.',PLoS ONEhttp://europepmc.org/articles/PMC2809091?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Second, during urea denaturation experiments, the thermodynamic parameters of the wild-type and tetramer interface mutants are almost identical.
Sujithkumar Murugan, Hui-Chih Hung 2012, 'Biophysical Characterization of the Dimer and Tetramer Interface Interactions of theHuman Cytosolic Malic Enzyme', PLoS ONE10.1371/journal.pone.0050143. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)