Studies of the function of the cytoplasmic domain of the myelin Po protein.
Item
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Title
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Studies of the function of the cytoplasmic domain of the myelin Po protein.
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Identifier
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AAI9707165
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identifier
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9707165
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Creator
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Wong, Man-Har.
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Contributor
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Adviser: Marie T. Filbin
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Date
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1996
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Biochemistry | Biology, Neuroscience | Biology, Cell
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Abstract
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The extracellular domain of Po is known to be involved directly in adhesion via homophilic interactions, however, the function of the cytoplasmic domain of Po is not clear. Two tuncated Po cDNAs were created; one missing the nucleotides coding for the last 52 amino acids and the other missing the nucleotides coding for the last 59 amino acids of Po's cytoplasmic domain. These truncated Po cDNAs were transfected into Chinese hamster ovary (CHO) cells and the respective proteins, designated as TPo52 and TPo59, were expressed, glycosylated and reached the cell surface. However, neither of the truncated Po proteins induced cell-cell adhesion when compared to the cells expressing full-length Po. Hence, the cytoplasmic domain of Po is essential and must be intact for adhesion of its extracellular domain to take place.;The relationship between Po and the cytoskeleton was studied. After extraction in the detergent NP-40, 25-30% of full-length Po, 5-10% of TPo52 and none of TPo59 was found in the insoluble fraction. These results indicate that full-length Po associates with cytoskeleton and that truncation of Po's cytoplasmic domain reduces this interaction. Colchicine, which disrupts microtubules, prevents the adhesion of the cells expressing full-length Po, supporting the idea that an interaction of Po with the cytoskeleton is critical for adhesion to take place. A protein of approximately 38 kD that co-precipitates with full-length Po was identified, suggesting that Po may indirectly interact with cytoskeleton through this linker protein.;Full-length and truncated Po cDNAs were transfected together into CHO cells at a 1:1 ratio. In the co-expressors both full-length and truncated Po protein were expressed, glycosylated and reached the cell surface. The truncated Po proteins prevented the adhesion of the full-length Po as the co-expressors were not adhesive. It is concluded that the truncated Po proteins have a dominant:negative effect on the adhesion of the full-length Po.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
