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001-es BibID:	BIBFORM046090
Első szerző:	Bacsó Zsolt (biofizikus)
Cím:	Raft and cytoskeleton associations of an ABC transporter : P-glycoprotein / Zsolt Bacso, Henrietta Nagy, Katalin Goda, László Bene, Ferenc Fenyvesi, János Matkó, Gábor Szabó
Dátum:	2004
ISSN:	0196-4763
Megjegyzések:	A novel flow cytometric assay has been described in an accompanying report (Gombos et al., METHODS: The kinetics of the decrease in immunofluorescence intensity was analyzed after the addition of the raft-preserving Triton X-100 or Nonidet P-40, both of which disrupt the entire membrane. Mild treatments by both detergents leave cells attached to only those proteins that are anchored to the cytoskeleton by rafts or independent of rafts. Agents that affect microfilaments and modulate membrane levels of cholesterol by cyclodextrin were used to distinguish between the raft-mediated and non-raft-related associations of the Pgp. Confocal microscopy and flow cytometric fluorescence energy transfer measurements were used to confirm colocalization of Pgp with raft constituents. RESULTS: The assay was proved to be sensitive enough to resolve differences between the resistance of UIC2-labeled cell-surface Pgps to Triton X-100 versus Nonidet P-40. Approximately 34% of the UIC2 Fab-labeled Pgp molecules were associated with the cytoskeleton through detergent-resistant, cholesterol-sensitive microdomains or directly, whereas approximately 15% were found to be directly linked to the cytoskeleton. Accordingly, confocal microscopy showed that Pgps colocalize with raft markers, mainly in microvilli. Fluorescence resonance energy transfer efficiency data indicating molecular proximity between Pgp and the raft markers CD44, CD59, and G(M1)-gangliosides also suggested that a significant fraction of Pgps resides in raft microdomains. Raft association of Pgp appears to be of functional significance because its modulation markedly affected drug pumping. CONCLUSIONS: By using the flow cytometric detergent resistance assay in kinetic mode, we were able to assess the extent of raft association and actin cytoskeleton anchorage of Pgp expressed at physiologically relevant levels. We demonstrated that a significant fraction of Pgp is raft associated on LS-174-T human colon carcinoma cells and that this localization may influence its transporter function. The kinetic flow cytometric detergent resistance assay presented in this report is considered to be generally applicable for the analysis of molecular interactions of membrane proteins expressed at low levelsújratöltve - BIBFORM004828
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Cytometry. - 61 : 2 (2004), p. 105-116. -
További szerzők:	Nagy Henrietta Goda Katalin (1969-) (biofizikus) Bene László (1963-) (biofizikus) Fenyvesi Ferenc (1977-) (gyógyszerész, gyógyszertechnológus) Matkó János (1952-) (biológus) Szabó Gábor (1953-) (biofizikus)
Pályázati támogatás:	T032563 OTKA 034393 OTKA T046945 OTKA
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM046091
Első szerző:	Gombos Imre
Cím:	Cholesterol sensitivity of detergent resistance : a rapid flow cytometric test for detecting constitutive or induced raft association of membrane proteins / Imre Gombos, Zsolt Bacsó, Cynthia Detre, Henrietta Nagy, Katalin Goda, Márton Andrásfalvy, Gábor Szabó, János Matkó
Dátum:	2004
ISSN:	0196-4763
Megjegyzések:	Lipid rafts are cholesterol- and glycosphingolipid-rich microdomains in the cellular plasma membranes that play critical roles in compartmentalization (concentration, coupling, and isolation) of receptors and signal molecules. Therefore, detecting constitutive or induced raft associations of such proteins is of central interest in cell biology. This has mostly been done with time- and cell-consuming immunobiochemical techniques affected by several sources of artifacts. A flow cytometric analysis of immunocytochemical staining under differential circumstances of detergent treatment offers a new alternative to this method. METHODS: Membrane microdomains are resistant to nonionic detergents due to extensive, strong interactions between their molecular constituents. We used this feature to develop a rapid flow cytometric assay of differential detergent resistance based on immunocytochemical labeling of extracellular domain epitopes in membrane proteins. Data evaluation is based on comparative detection of their detergent solubility without and with cholesterol depletion of cell membranes, resolved by moderate concentrations of nonionic detergents. RESULTS: Nonionic detergents Triton X-100 and Nonidet-40 (0.05-0.1%) in cold or Brij-98 (0.1-0.5%) at 37 degrees C efficiently resolved detergent solubility or resistance of many lymphocyte cell surface proteins. Kinetic data revealed that a short (5-10 min) detergent treatment is sufficient for this assay. Comparison of detergent solubility in untreated and cholesterol-depleted cells differentiated membrane proteins associated with or excluded from raft microdomains, respectively. Confocal microscopy showed that this mild detergent treatment leaves the cytoskeleton of the cells intact, with a detectable expression of raft marker detergent-resistant proteins attached to it. An induced association with rafts of immunoglobulin E receptors upon antigen cross-linking was also easily detectable in rat mast cells by this approach. CONCLUSIONS: A protocol is proposed for a rapid (5-10 min) test of detergent resistance of membrane proteins in cells. The approach requires only a small amount of cells (10(4)/sample) and offers a good resolution of detergent solubility or resistance of membrane proteins, also in terms of the underlying mechanisms, with an advantage of applicability for all conventional bench-top flow cytometers.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Cytometry. Part A. - 61A : 2 (2004), p. 117-126. -
További szerzők:	Bacsó Zsolt (1963-) (biofizikus) Detre, Cynthia Nagy Henrietta Goda Katalin (1969-) (biofizikus) Andrásfalvy Márton Szabó Gábor (1953-) (biofizikus) Matkó János (1952-) (biológus)
Pályázati támogatás:	T034393 OTKA TS044711 OTKA T032563 OTKA T046945 OTKA
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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