Spectrins its structure,function and role in animal cells
and role in animal
• Spectrin is a cytoskeletal protein.
• First isolated as a major protein
component of human red blood
• Forms pentagonal or hexagonal
arrangements, playing an important
role in maintenance of plasma
membrane integrity and
Spectrins: several genes and numerous isoforms widely
distributed in all metazoan cells
• Exist mainly as heterotetramers
made of various a and b subunit
• SPTA1 and SPTAN,SPTB,SPTBN1,
SPTBN2, SPTBN4 & SPTBN5
• C.elegans and D.melanogaster-a-
spectrin bG & bH-spectrin.
• a-Spectrins contain 20 spectrin
repeats, b-spectrins are made of
17 spectrin repeats (b1-b17), while
the heavy bV-spectrins contain 30
• Ankyrin, 4.1 complex-which
includes actin, dematin,adducin,
tropomyosin and tropomodulin,
Spectrins are a structural platform for stabilization
and activation of membrane microdomains
• Spectrin-based skeleton
participates in the
organization of specialized
• No accumulation of membrane
partners at the appropriate
site within the membrane.
• Spinocerebellar ataxia type 5
(SCA5) and neurodegenerative
• Tremors and contraction of the
• Loss of Na+K+ ATPase from the
basolateral domain of
epithelial cells- Drosophila.
Spectrins are multifunctional proteins involved
in regulation of cell morphology and mechanical
• Hereditary hemolytic anemia
associated with mutations in
both aI- and bI-spectrins.
• In epithelial cells, knockdown
of bII-spectrin results in loss of
the lateral membrane,
expansion of the apical and
basal membrane area, and
conversion of cells from
columnar to squamous
• a- and b-spectrins are required
during nervous system
Spectrins, cell cycle and DNA repair
• The presence of spectrin in a
complex including TGFb-R1-
• Spectrin depleted melanoma
cells cell cycle arrest in the G1
• aII-spectrin binds to DNA at the
sites of damage and acts as a
scaffold, recruiting of repair
• Decreased cell growth and
Spectrin contributes with actin to cell adhesion
• Spectrin depleted cells exhibited modifications of the actin
cytoskeleton,such as loss of stress fibers, alterations of focal
contacts and modified expression of some integrins.
Control of activation of transmembrane proteins
• Spectrin-based skeleton via its two
major proteins, spectrin and
ankyrin, directly binds CD45 in
• Spectrin aggregates contain several
proteins, such as hsp70, receptor
for activated C kinase-1 (RAC-1)
• Participation of spectrin in
signaling function in lymphocytes.
• PKCh relationship to spectrin and its
participation in regulating early
steps of apoptosis.
Spectrin functions can be regulated by posttranslational
endocytosis, vertebrate lens
the central nervous system.
• b-Spectrin phosphorylation
essential in destabilization of
the erythrocyte membrane
• Proteolysis of spectrin .
Spectrin Plays a Critical Role in Platelet Formation
• Diane Krause, MD, PhD
1/6988.aspx September 1,
• Using a novel spectrin
• During megakaryocyte
maturation, an extensive
invaginated membrane system
forms. Without intact spectrin
lacked this extensive
Shigella flexneri utilize the spectrin cytoskeleton
during invasion and comet tail generation
• Tyson J Ruetz1, Ann E
Lin1 and Julian A Guttman* 2012
• Following internalization, all
three proteins are recruited to
the internalized bacteria, spectrin
recruitment to those structures in
the absence of adducin or p4.1.
• Invasion of intestinal epithelial
cells and comet tail-based
motility in host cells are key for S.
flexneri to access replicative
niches and disseminate
throughout host tissues .
• Spectrin-based skeleton as an actor in cell signaling B.
Machnicka • R. Grochowalska • D. M. Bogusławska •A. F.
Sikorski • M. C. Lecomte Published: 30 August 2011