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ß-Spectrins and their Homologues -
Comparative Studies and Consensus
Sequence Construction
Anna FOGTMAN
Institute of Biochemistry and Molecular Biology, University of Wroclaw, Poland
Abstract.
The E-spectrin family of proteins was the subject of the analysis of amino
acid replacenents at aligned positions. The homologous and non-homologous
positions were subjected to an analysis of the interrelations among occurring
residues and the mechanism of variability using the algorithm of genetic
semihomology [6]. 67 E-spectrin sequences were collected and 55 of them were
subjected to an comparative analysis. After in-depth studies of the global multiple
alingnment, a consensus sequence was construscted. It was the base of the detailed
analysis of genetic relations among all the amino acid residues occuring the same
positions of homologous sequences. Such examination shows a detailed picture of
the relations among the representatives of the E-spectrin family and gives a
possibility of following the evolutionary paths of the protein family arising, what is
the base of further analytic examinations of the E-spectrin family.
Introduction
Spectrin was first identified as a major component of the erythrocyte membrane
cytoskeleton, controlling its organization, stability and shape. Nowadays it is known, that
spectrins are common in cells of all types of tissues of
Vertebrates
and
Invertebrates
; they
take part in many processes essential for normal functioning of a cell. Spectrin is a
cytoskeletal protein important for keeping the right shape of the cell, resilience of a
membrane during a mechanical stress. It determines the distribution of transmembrane
proteins and the organization of organelles in the cytoplasm. Spectrin, through its
interactions with the hydrophobic part of the cell membrane, is a factor taking part in
building the system of actin filaments. Recently a new role of this protein has been found as
a participant in secretic pathways of cells [Beck and Nelson, 1998; De Matties and Morrow,
1998]. Diverse isoforms of spectrin and spectrin binding proteins - ankyrins are present on
the surface of Golgi structures, transported intermediates and on membranes of
endocythotic pathway. Spectrin plays a crucial role for stabilization of the cell membrane,
organization of domains of integral proteins, controling mobility of the membrane
receptors, cell adhesion, nerve impulse transduction, synthesis of the secretic vesicles and
their transport among organelles, also for development and morphogenesis of the embrion
cells. Changes in the primary structure that are caused by genetic mutations, cause injuries
or absence of the membrane cytoskeleton proteins, which disturb the interactions:
cytoskeleton - cell membrane. Those disturbations lead to deformations, loss of elasticity
and diminish of the cell surface. An example of such disturbances are hereditary hemolytic
anaemias.
e-mail:
fogi@grid.icm.edu.pl
