A new variant of the alpha subunit of spectrin in hereditary elliptocytosis
S Lambert and S Zail
A kindred is described in which two brothers with a poikilocytic variant of
hereditary elliptocytosis (HE) were found to have a defect of spectrin
dimer association and a decreased spectrin-band 3 ratio. Two-dimensional
gel electrophoresis of limited tryptic digests of their spectrin revealed
decreased amounts of the alpha I domain when compared with control digests
and the appearance of two major peptides with mol wts of 43,000 and 42,000
and isoelectric points (5.75 to 5.85) more basic than the alpha I domain.
Tryptic digests of spectrin from the asymptomatic mother of the two
brothers were normal. Immunoblots of the two-dimensional gels using an
antiserum to the alpha I domain revealed that the 43,000- and 42,000-dalton
peptides were derived from the alpha I domain, along with a series of lower
mol wt peptides, some of which were below the detection limits of Coomassie
blue-stained gels. Limit chymotryptic maps of 125I-labeled tryptic peptides
confirmed that the 43,000- and 42,000-dalton peptides were derived from the
alpha I domain. This kindred represents a new structural variant of
spectrin in HE in that the major abnormal tryptic peptides derived from the
alpha I domain have lower mol wts and more basic isoelectric points than
hitherto described.
Volume 69,
Issue 2,
pp. 473-478,
02/01/1987
Copyright © 1987 by The American Society of Hematology
