An '''alpha/beta barrel''' is a protein fold formed by units composed of a short α-helix followed by two anti-parallel β-strands, followed by an α-helix and a β-strand; the three β-strands form a β-sheet that runs parallel to the barrel and the α-helix is in the outside of the barrel but does not contact the α-helices of the other repeats like in TIM barrels.
The protein structures known for this fold come proteins from the eukaryotic and archaeal initiation factor 6 family, namely the ''Methanococcus jannaschii'' aIF6 and ''Saccharomyces cerevisiae'' eIF6,<ref>{{cite journal |vauthors=Groft CM, Beckmann R, Sali A, Burley SK |title=Crystal structures of ribosome anti-association factor IF6 |journal=Nat. Struct. Biol. |volume=7 |issue=12 |pages=1156–64 |date=December 2000 |pmid=11101899 |doi=10.1038/82017 |s2cid=35762049 }}</ref> and from the eIF6 from ''Dictyostelium discoideum''.<ref>{{cite journal |vauthors=Weis F, Giudice E, Churcher M, Jin L, Hilcenko C, Wong CC, Traynor D, Kay RR, Warren AJ |title=Mechanism of eIF6 release from the nascent 60S ribosomal subunit |journal=Nat. Struct. Mol. Biol. |volume=22 |issue=11 |pages=914–9 |date=November 2015 |pmid=26479198 |pmc=4871238 |doi=10.1038/nsmb.3112 }}</ref>
These alpha/beta barrels are commonly occurring motifs constructed from repetitions of the beta-alpha-beta loop motif. This alpha/beta barrel is a domain of pyruvate kinase enzyme. <ref>{{Cite book |pmid=21195229 |date=2011 |last1=Lee |first1=J. C. |last2=Herman |first2=P. |chapter=Structural and Functional Energetic Linkages in Allosteric Regulation of Muscle Pyruvate Kinase |title=Biothermodynamics, Part C |series=Methods in Enzymology |volume=488 |pages=185–217 |doi=10.1016/B978-0-12-381268-1.00008-2 |isbn=9780123812681 }}</ref> == References == {{reflist}}
Category:Protein structure Category:Protein folds Category:Protein tandem repeats Category:Protein domains