The eight-cysteine motif, a versatile structure in plant proteins.
A number of protein sequences deduced from the molecular analysis of plant cDNA or genomic libraries can be grouped in relation to a defined number of cysteine residues located in distinct positions of their sequences. This is the case for a group of around 500 polypeptides from different species that contain a small domain (less than 100 amino acids residues) displaying a pattern of eight-cysteines in a specific order. The plant sequences containing this motif belong to proteins having different functions, ranging from storage, protection, enzyme inhibition and lipid transfer, to cell wall structure. The eight-cysteine motif (8CM) appears to be a structural scaffold of conserved helical regions connected by variable loops, as observed by three-dimensional structure analysis. It is proposed that the cysteine residues would form a network of disulfide bridges necessary, for the maintenance of the tertiary structure of the molecule together with the central helical core, while the variable loops would provide the sequences required for the specific functions of the proteins.
José-Estanyol
Matilde
M
Laboratori de Genètica Molecular i Vegetal, Consorci CSIC-IRTA, Jordi Girona 18-26, 08034 Barcelona, Spain. mjegmp@ibmb.csic.es
Gomis-Rüth
F Xavier
FX
Puigdomènech
Pere
P
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D010940:Plant Proteins