Calcium determines the supramolecular organization of fibrillin-rich microfibrils.
J Cell Biol
; 141(3): 829-37, 1998 May 04.
Article
em En
| MEDLINE
| ID: mdl-9566980
ABSTRACT
Microfibrils are ubiquitous fibrillin-rich polymers that are thought to provide long-range elasticity to extracellular matrices, including the zonular filaments of mammalian eyes. X-ray diffraction of hydrated bovine zonular filaments demonstrated meridional diffraction peaks indexing on a fundamental axial periodicity (D) of approximately 56 nm. A Ca2+-induced reversible change in the intensities of the meridional Bragg peaks indicated that supramolecular rearrangements occurred in response to altered concentrations of free Ca2+. In the presence of Ca2+, the dominant diffracting subspecies were microfibrils aligned in an axial 0.33-D stagger. The removal of Ca2+ caused an enhanced regularity in molecular spacing of individual microfibrils, and the contribution from microfibrils not involved in staggered arrays became more dominant. Scanning transmission electron microscopy of isolated microfibrils revealed that Ca2+ removal or addition caused significant, reversible changes in microfibril mass distribution and periodicity. These results were consistent with evidence from x-ray diffraction. Simulated meridional x-ray diffraction profiles and analyses of isolated Ca2+-containing, staggered microfibrillar arrays were used to interpret the effects of Ca2+. These observations highlight the importance of Ca2+ to microfibrils and microfibrillar arrays in vivo.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Cálcio
/
Proteínas da Matriz Extracelular
/
Proteínas dos Microfilamentos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
1998
Tipo de documento:
Article