“ST turn”的意思、由来-开放百科全书

The ST turn is a structural feature in proteins and polypeptides.^[1] Each consists of three amino acid residues (labeled i, i + 1 and i + 2) in which residue i is a serine (S) or threonine (T) that forms a hydrogen bond from its sidechain oxygen group to the mainchain NH group of residue i + 2.^[2]^[3]

Similar motifs occur with aspartate or asparagine as residue i, called asx turn. Four types of asx turn and ST turn can be distinguished: types I, I’, II and II’. These categories correspond (via sidechain-mainchain mimicry of residue i) to those of the more abundant hydrogen-bonded beta turns, which have four residues and a hydrogen bond between the CO of residue i and the NH of residue i + 3. Regarding their occurrence in proteins, they differ in that type I is the commonest of the four beta turns while type II’ is the commonest of the ST and asx turns.

Asx and ST turns both occur frequently at the N-termini of α-helices,^[4]^[5]^[6]^[7] as part of asx motifs or ST motifs, with the asx, serine or threonine as the N cap residue. They are thus often regarded as helix capping features.

Evidence for a functionally relevant ST turn is provided in the CDR3 region of the T-cell receptor (B chain, V domain) ^[8]

A proportion of ST turns are accompanied by a mainchain-mainchain hydrogen bond that qualifies them as ST motifs.

References

1. ^{{cite journal|last=Duddy|first=WJ|author2=Nissink WMJ |title=Mimicry by asx- and ST-turns of the four main types of β-turn in proteins|journal=Protein Science|year=2004|volume=13|issue=11|pages=3051–3055|doi=10.1110/ps.04920904|pmid=15459339|last3=Allen|first3=Frank H.|last4=Milner-White|first4=E. James|pmc=2286581}}
2. ^{{cite journal|last=Leader|first=DP|author2=Milner-White EJ |title=Motivated Proteins: A web application for studying small three-dimensional protein motifs|journal=BMC Bioinformatics|year=2009|volume=10|pages=60|doi=10.1186/1471-2105-10-60|pmid=19210785|pmc=2651126}}
3. ^{{cite journal|last=Golovin|first=A|author2=Henrick K |title=MSDmotif: exploring protein sites and motifs|journal=BMC Bioinformatics|year=2008|volume=9|pages=312|doi=10.1186/1471-2105-9-312|pmid=18637174|pmc=2491636}}
4. ^{{cite journal|last=Doig|first=AJ|author2=Macarthur MW |title=Structures of N-termini of helices in proteins|journal=Protein Science|volume=6|issue=1|pages=147–155|doi=10.1002/pro.5560060117|pmid=9007987|pmc=2143508|year=2008|last3=MacArthur|first3=Malcolm W.|last4=Thornton|first4=Janet M.}}
5. ^{{cite journal|last=Presta|first=LG|author2=Rose GD |title=Helix Caps|journal=Science|year=1988|volume=240|issue=4859|pages=1632–1641|doi= 10.1126/science.2837824|pmid=2837824|bibcode=1988Sci...240.1632P}}
6. ^{{cite journal|last=Aurora|first=R|author2=Rose GD |title=Helix Capping|journal=Protein Science|year=1998|volume=7|issue=1|pages=21–38|doi= 10.1002/pro.5560070103|pmid=9514257|pmc=2143812}}
7. ^{{cite journal|last=Gunasekaran|first=K|author2=Nagarajam HA |title=Sterochemical punctuation marks in protein structure|journal=Journal of Molecular Biology|year=1998|volume=275|issue=5|pages=917–932|doi= 10.1006/jmbi.1997.1505|pmid=9480777|last3=Ramakrishnan|first3=C|last4=Balaram|first4=P}}
8. ^{{cite journal|last=Yassai|first=MB|author2=Demus W|author3=Gorski J|title=Structural and Mechanistic Implications of Rearrangement Frequencies within Human TCRBV Genes|journal=J Immunol|volume=199|issue=3|pages=1142–1152|year=2017|doi=10.4049/jimmunol.1601450|pmid=28659354|pmc=5659713}}

References

External links