Ultrastructural
Distribution of the S100A1 Ca2+-Binding Protein
in the Human Heart
B. MACO1,
A. MANDINOVA2, M. B. DÜRRENBERGER2,
B. W. SCHÄFER3, B. UHRÍK1,
C. W. HEIZMANN3
1Institute of
Molecular Physiology and Genetics, Slovak Academy
of Sciences, Bratislava, Slovakia, 2Maurice E. Müller-Institute,
Biocentrum, University of Basel, Basel,
Switzerland, 3Division of
Clinical Chemistry and Biochemistry, Department
of Pediatrics, University of Zurich, Zurich,
Switzerland
Received
October 26, 2000
Accepted March 26, 2001
Summary
Impaired
calcium homeostasis and altered expression of
Ca2+-binding proteins are associated with
cardiomyopathies, myocardial hypertrophy,
infarction or ischemia. S100A1 protein with its
modulatory effect on different target proteins
has been proposed as one of potential candidates
which could participate in these pathological
processes. The exact localization of S100A1 in
human heart cells on the ultrastructural level
accompanied with biochemical determination of its
target proteins may help clarify the role of
S100A1 in heart muscle. In the present study the
distribution of the S100A1 protein using
postembedding (Lowicryl K4M) immunocytochemical
method in human heart muscle has been determined
quantitatively, relating number of antigen sites
to the unit area of a respective structural
component. S100A1 antigen sites have been
detected in elements of sarcoplasmic reticulum
(SR), in myofibrils at all levels of sarcomere
and in mitochondria, the density of
immunolabeling at Z-lines being about 3 times and
at SR more than 5 times higher than
immunolabeling of remaining structural
components. The presence of the S100A1 in SR and
myofibrils may be related to the known target
proteins for S100A1 at these sites.
Key words
Human
heart muscle · Ca2+-binding proteins · S100A1
· Immunocytochemistry
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B.
Uhrík, Institute of Molecular Physiology and
Genetics, Slovak Academy of Sciences, Vlárska 5,
833 34 Bratislava, Slovak Republic. Fax:
+421-2-5477-3666, E-mail: umfguhrk@savba.savba.sk
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