In the erythrocyte, ankyrin is the major adapter protein linking mutation of the linker sequences that join helices C and A in repeat tetramers of band 3 to the spectrin–actin cytoskeleton. This linkage units that intervene between the two functional sites, mutations that involves a direct interaction between ankyrin and the 14th–15th repeat presumably block repeat-to-repeat transfer of conformational informaunit of b-spectrin. The spectrin cytoskeleton itself is stabilized by tion; (ii) mutations in a-spectrin repeats 4 to 6 that disrupt the ability the self-association of spectrin heterodimers into tetramers and larger of this region to trans-regulate ankyrin binding by the adjacent boligomers, a process mediated by the 17th repeat unit of b-spectrin spectrin repeats 14–15; and (iii) exon-skipping mutations that shorten and a short NH2-terminal sequence in a-spectrin. The self-association a-spectrin and force repeats 4 to 6 to fall out-of-register with the of spectrin and its ankyrin-mediated membrane binding have generally ankyrin-binding motif in b-spectrin. Collectively, these results demonbeen considered independent events.We now demonstrate that spectrin strate a molecular mechanism whereby a membrane receptor can diself- association, the binding of spectrin to ankyrin, and the binding of rectly promote cytoskeletal assembly. q 2001 Academic Press ankyrin to the 43-kDa cytoplasmic domain of band 3 (cdb3) are coupled in a positively cooperative way. In solution, [125I]-labeled ankyrin was found by ND-PAGE3 to enhance the affinity of spectrin self-association by 10-fold. The reciprocal process was also true, in that spectrin tetramers and oligomers bound ankyrin with enhanced affinity relative to dimer spectrin. Saturation of the b-spectrin self-association site by INTRODUCTION an NH2-terminal 80-kDa a-spectrin peptide enhanced the affinity of spectrin dimer for ankyrin, indicating a direct relationship between ankyrin binding and the occupancy of the b-spectrin self-association During the process of erythroid maturation the cortical site. cdb3 accentuated these cooperative interactions. Several inherited spectrin mutations that cause hemolytic disease but that do not directly cytoskeleton is formed by interactions between ankyrin, destabilize the self-association or ankyrin-binding sites can be ex- band 3 (the membrane anion transporter 1, AE1), and specplained by these results. Three classes of mutations appear to disrupt trin (for reviews, see Lux and Palek, 1995; Morrow et al., cooperative coupling between self-association and ankyrin binding:
Spectrin oligomerization is cooperatively coupled to membrane assembly: A linkage targeted by many hereditary hemolytic anemias? / Giorgi, Mauro; Cianci, Carol D.; Gallagher, Patrick G.; Morrow, Jon S.. - In: EXPERIMENTAL AND MOLECULAR PATHOLOGY. - ISSN 0014-4800. - STAMPA. - 70:3(2001), pp. 215-230. [10.1006/exmp.2001.2377]
Spectrin oligomerization is cooperatively coupled to membrane assembly: A linkage targeted by many hereditary hemolytic anemias?
GIORGI, MAURO;
2001
Abstract
In the erythrocyte, ankyrin is the major adapter protein linking mutation of the linker sequences that join helices C and A in repeat tetramers of band 3 to the spectrin–actin cytoskeleton. This linkage units that intervene between the two functional sites, mutations that involves a direct interaction between ankyrin and the 14th–15th repeat presumably block repeat-to-repeat transfer of conformational informaunit of b-spectrin. The spectrin cytoskeleton itself is stabilized by tion; (ii) mutations in a-spectrin repeats 4 to 6 that disrupt the ability the self-association of spectrin heterodimers into tetramers and larger of this region to trans-regulate ankyrin binding by the adjacent boligomers, a process mediated by the 17th repeat unit of b-spectrin spectrin repeats 14–15; and (iii) exon-skipping mutations that shorten and a short NH2-terminal sequence in a-spectrin. The self-association a-spectrin and force repeats 4 to 6 to fall out-of-register with the of spectrin and its ankyrin-mediated membrane binding have generally ankyrin-binding motif in b-spectrin. Collectively, these results demonbeen considered independent events.We now demonstrate that spectrin strate a molecular mechanism whereby a membrane receptor can diself- association, the binding of spectrin to ankyrin, and the binding of rectly promote cytoskeletal assembly. q 2001 Academic Press ankyrin to the 43-kDa cytoplasmic domain of band 3 (cdb3) are coupled in a positively cooperative way. In solution, [125I]-labeled ankyrin was found by ND-PAGE3 to enhance the affinity of spectrin self-association by 10-fold. The reciprocal process was also true, in that spectrin tetramers and oligomers bound ankyrin with enhanced affinity relative to dimer spectrin. Saturation of the b-spectrin self-association site by INTRODUCTION an NH2-terminal 80-kDa a-spectrin peptide enhanced the affinity of spectrin dimer for ankyrin, indicating a direct relationship between ankyrin binding and the occupancy of the b-spectrin self-association During the process of erythroid maturation the cortical site. cdb3 accentuated these cooperative interactions. Several inherited spectrin mutations that cause hemolytic disease but that do not directly cytoskeleton is formed by interactions between ankyrin, destabilize the self-association or ankyrin-binding sites can be ex- band 3 (the membrane anion transporter 1, AE1), and specplained by these results. Three classes of mutations appear to disrupt trin (for reviews, see Lux and Palek, 1995; Morrow et al., cooperative coupling between self-association and ankyrin binding:I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
