Two elliptocytogenic alpha I/74 variants of the spectrin alpha I domain. Spectrin Culoz (GGT----GTT; alpha I 40 Gly----Val) and spectrin Lyon (CTT----TTT; alpha I 43 Leu---Phe).
Spectrin alpha I/74 elliptocytosis results from abnormalities involving the "head" region of spectrin dimer. Increased susceptibility to trypsin enhances cleavage of the alpha spectrin chain, yielding an increased amount of the alpha I 74-kD fragment at the expense of the alpha I 80-kD parent fragment. Recently we showed that the mutations causing the Sp alpha I/74 abnormality may lie in the alpha- or the beta-chain, and that spectrin Culoz and spectrin Lyon were two (alpha I/74) alpha-variants, respectively. We now show that the spectrin Culoz alpha I domain undergoes prominent tryptic cleavage after Lys 42, whereas cleavage prevails after Arg 39 in spectrin Lyon. Applying the polymerase chain reaction (PCR) technique to exon 2 of the spectrin alpha I domain, we have established that the mutation responsible for spectrin Culoz is alpha I 40 Gly----Val; GGT----GTT. Applying the PCR technique to the cDNA derived from reticulocyte mRNA, we have shown that the mutation responsible for spectrin Lyon is alpha I 43 Leu----Phe; CTT----TTT. Studies of normal controls and of family members using dot blot hybridization with allele-specific oligonucleotide probes confirmed these results. Variants such as spectrin Culoz and spectrin Lyon should provide insight into a region that participates in spectrin dimer self-association and whose susceptibility to proteolysis must reflect subtle conformational changes.
Morlé
L
L
Centre National de la Recherche Scientifique (CNRS) URA 1171, Faculté de Médecine Grange-Blanche, Lyon, France.
Roux
A F
AF
Alloisio
N
N
Pothier
B
B
Starck
J
J
Denoroy
L
L
Morlé
F
F
Rudigoz
R C
RC
Forget
B G
BG
Delaunay
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D004612:Elliptocytosis, Hereditary / Q000235:genetics*; D005796:Genes; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D015345:Oligonucleotide Probes; D010446:Peptide Fragments / Q000032:analysis; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D013049:Spectrin / Q000235:genetics*
D015345:Oligonucleotide Probes; D010446:Peptide Fragments; D012333:RNA, Messenger; D013049:Spectrin