title: Sp alpha I/65: a new variant of the alpha subunit of spectrin in hereditary elliptocytosis.
abstract: Two molecular defects involving the spectrin heterodimer (SpD) contact site of the alpha chain (the alpha I domain) were previously identified using limited tryptic digestion followed by two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both are characterized by atypical peptide maps which reveal a marked decrease of the 80,000-dalton alpha I domain and a formation of new major peptides of either 74,000 (Sp alpha I/74) or 46,000 (Sp alpha I/46) daltons. We now report a third variant of the spectrin alpha chain, designated Sp alpha I/65, in three unrelated black families. In all three probands, the percentage of SpD in the low ionic strength (O degrees C) membrane extracts was increased to 19% to 32%. One- and two-dimensional electrophoretic separations of limited tryptic digests of spectrin from all three probands revealed a decrease of the alpha I domain of spectrin and the concomitant appearance of peptides at 65,000 daltons and isoelectric points ranging from 5.2 to 5.3. The abnormal 65,000-dalton peptides could be stained with an antiserum which had been raised against the alpha I domain, indicating that it was derived from the alpha I domain.
mesh_terms: D000328:Adult; D004591:Electrophoresis, Polyacrylamide Gel; D004612:Elliptocytosis, Hereditary / Q000097:blood* / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D007525:Isoelectric Focusing; D046911:Macromolecular Substances; D008875:Middle Aged; D010455:Peptides / Q000032:analysis; D012967:Sodium Dodecyl Sulfate; D013049:Spectrin / Q000032:analysis* / Q000235:genetics
chemical_list: D046911:Macromolecular Substances; D010455:Peptides; D013049:Spectrin; D012967:Sodium Dodecyl Sulfate