Genetic microheterogeneity of human transthyretin detected by IEF.
Mutations of the human transthyretin (TTR) gene have attracted medical interest as a cause of amyloidosis. Recently, we have described in detail an electrophoretic procedure with PAGE followed by IEF in urea gradients for the study of the microheterogeneity of TTR monomers (Altland, K., Winter, P., Sauerborn, M. K., Electrophoresis 1999, 20, 1349-1364). In this paper, we present a study on 49 different mutations of TTR including 33 that result in electrically neutral amino acid substitutions. The aims of the investigation were to test the sensitivity of the procedure to detect TTR variants in patients with TTR amyloidosis and their relatives and to identify some common characteristics that could explain the amyloidogenicity of these variants. We found that all tested amyloidogenic mutations could be detected by our method with the exception of those for which the corresponding variant was absent in plasma samples. Most of the electrically neutral amyloidogenic TTR variants had in common a reduced conformational stability of monomers by the activity of protons and urea. For three variants, e.g. TTR-F64L, TTR-I107V and TTR-V122I, the monomers had a conformational stability close to that of normal monomers but we found experimental and structural arguments for a weakening of the monomer-monomer contact. All types of amyloidogenic mutations affected the stability of TTR tetramers.
Altland
Klaus
K
Institut für Humangenetik, Justus-Liebig-Universität, Giessen, Germany. Klaus.Altland@humangenetik.med.uni-giessen.de
Benson
Merrill D
MD
Costello
Catherine E
CE
Ferlini
Alessandra
A
Hazenberg
Bouke P C
BP
Hund
Ernst
E
Kristen
Arnt V
AV
Linke
Reinhold P
RP
Merlini
Giampaolo
G
Salvi
Fabrizio
F
Saraiva
Maria J
MJ
Singer
Reinhard
R
Skinner
Martha
M
Winter
Pia
P
D019943:Amino Acid Substitution / Q000235:genetics; D000686:Amyloidosis / Q000097:blood / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing / Q000379:methods*; D009154:Mutation / Q000235:genetics*; D011228:Prealbumin / Q000032:analysis* / Q000737:chemistry / Q000235:genetics*; D011487:Protein Conformation; D017510:Protein Folding; D013329:Structure-Activity Relationship; D017186:Titrimetry; D014508:Urea / Q000737:chemistry
D011228:Prealbumin; D014508:Urea