1H-NMR analysis of CD3-epsilon reveals the presence of turn-helix structures around the ITAM motif in an otherwise random coil cytoplasmic tail.
The conformation adopted in solution by the cytoplasmic tail of CD3-epsilon has been analyzed by 1H-nmr. The cytoplasmic tail is mostly random coil expect for the amino acids conforming the immunoreceptor tyrosine-based activation motif (ITAM), YxxL/IxxxxxxxY xxL. Although the N-terminal Y xxL sequence of the motif is poorly folded, adopting 6-residue turn-like conformations with the Tyr side chain in two different orientations, the C-terminal Y xxL sequence is placed in a more complex structure involving a set of nonclassical alpha-helix turns and beta-turns that comprises 11 amino acids. This structure is not modified by phosphorylation of the tyrosine residue. The differences in the conformation adopted around the two tyrosines of the ITAM motif suggest that they may play different roles pertaining to either binding signal transducing proteins or, alternatively, proteins involved in other processes such as endoplasmic reticulum location.
Borroto
A
A
Centro de Biología Molecular Severo Ochoa, CSIC-Universidad Autónoma de Madrid Cantoblanco, Spain.
Jiménez
M A
MA
Alarcón
B
B
Rico
M
M
D000595:Amino Acid Sequence; D017252:CD3 Complex / Q000737:chemistry*; D003001:Cloning, Molecular; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D015398:Signal Transduction / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism
D017252:CD3 Complex; D011994:Recombinant Proteins; D014443:Tyrosine