COMPOSITION AND FUNCTION OF AN INVERTEBRATE ERYTHROCYTE CYTOSKELETON (MICROTUBULES, MARGINAL BAND, NUCLEATED ERYTHROCYTE, NOETIA PONDEROSA, SURFACE-ASSOCIATED).
Item
-
Title
-
COMPOSITION AND FUNCTION OF AN INVERTEBRATE ERYTHROCYTE CYTOSKELETON (MICROTUBULES, MARGINAL BAND, NUCLEATED ERYTHROCYTE, NOETIA PONDEROSA, SURFACE-ASSOCIATED).
-
Identifier
-
AAI8515637
-
identifier
-
8515637
-
Creator
-
JOSEPH-SILVERSTEIN, JACQUELYN ANN.
-
Contributor
-
William D. Cohen
-
Date
-
1985
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, General
-
Abstract
-
The cytoskeleton of the "blood clam" erythrocyte consists of a cold-labile marginal band (MB) of cross-bridged microtubules (MTs), the function of which in mature cells is unknown, and a surface-associated cytoskeleton (SAC). The identity of the MT cross-bridging proteins or any MB associated proteins (MB MAPs) is not known, nor is the composition of the SAC of invertebrate erythrocytes.;To identify MB MAPs and to study MB function in mature erythrocytes, cells with and without MBs were prepared under otherwise identical conditions. MB reassembly at 18-20(DEGREES)C after 0(DEGREES)C disassembly was blocked by nocodazole or colchicine, while MB disassembly at 0(DEGREES)C was blocked with taxol, thus producing cells with and without MBs at both room temperature and 0(DEGREES)C. In addition, MB assembly was induced at 0(DEGREES)C using taxol.;When subjected to the mechanical stress of fluxing through capillary tubes, cells without MBs buckled and folded while those with MBs remained normal in shape, demonstrating that the MB functions in maintaining the flattened elliptical shape of the cell during mechanical stress.;The cytoskeletal protein composition of cells with and without MBs was analyzed by SDS-PAGE, which revealed that in addition to tubulin, two proteins with Mrs of 80,000 and 105,000 were present in decreased amounts in cells lacking MBs. These two proteins may be MB MAPs. The Mr80,000 and Mr105,000 proteins, along with tubulin were also found in a soluble fraction from Brij-extracted cells incubated at 0(DEGREES)C to disassemble the MB.;The cytoskeleton of these erythrocytes was further characterized by SDS-PAGE as well as by Western blotting and indirect immunofluorescence microscopy using a panel of antibodies to known cytoskeletal proteins. The major protein components were identified as tubulin (which localized to the MB), actin (which localized to the SAC), and a 240,000Mr protein that comigrated with human (alpha)-spectrin, and reacted with an anti chicken erythrocyte"(alpha)-spectrin" antibody. This antibody localized to the SAC. Vimentin, a component of intermediate filaments was not identified here.;This work demonstrates a mechanical function for the MB in mature erythrocytes and identifies two proteins which cycle with the MB and therefore behave as MB MAPs. The protein composition of the invertebrate erythrocyte SAC shares some similarities with that of the vertebrate erythrocyte, but they are not identical.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Biology
