The QM Protein Associates with Ribosomes in the Rough Endoplasmic Reticulum
QM is a human cDNA originally isolated as a transcript elevated in a nontumorigenic Wilms' tumor microcell hybrid, relative to the tumorigenic parental cell line. Homologs of this gene have been identified from a large number of diverse eukaryotic species which demonstrate a high degree of cons...
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Published in | Biochemistry (Easton) Vol. 36; no. 27; pp. 8224 - 8230 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
08.07.1997
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Subjects | |
Online Access | Get full text |
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Summary: | QM is a human cDNA originally isolated as a transcript elevated in a nontumorigenic Wilms' tumor microcell hybrid, relative to the tumorigenic parental cell line. Homologs of this gene have been identified from a large number of diverse eukaryotic species which demonstrate a high degree of conservation. The functional importance implied by this strong conservation is supported by the observation that the disruption of the yeast homolog is lethal. In spite of its apparent importance, the function of the encoded protein remains elusive. Indirect immunofluorescent cell staining of cultured human, G401 cells with an antibody to the QM protein shows a punctate staining pattern in the cytoplasm with much of the signal in a perinuclear pattern. Subcellular fractionation demonstrated an association of QM protein with the rough endoplasmic reticulum. It was possible to disrupt this association by washing microsomal membranes with 1M NaCl, suggesting a peripheral association. Proteolytic latency studies showed the protein to be exposed on the cytoplasmic face of the membrane. In situ cross-linking followed by diagonal SDS gel analysis indicates that QM exists as a member of a large protein complex. In agreement with this, QM was found to copurify with the ribosome complex. Incubation with 1 M NaCl was found to disrupt this association while having no effect on the association of core ribosomal proteins. |
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Bibliography: | Abstract published in Advance ACS Abstracts, June 15, 1997. These studies were supported by NIH Grant CA19401. T.M.L. was supported by a National Science Foundation graduate fellowship. istex:15E1F7CE99CCF34965F240A2DE0A99D78A3D20D4 ark:/67375/TPS-C0N3GL8K-D ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi970288d |