Technical Reference #291

291.

Imaging Sites of Receptor Dephosphorylation by PTB1B on the Surface of the Endoplasmic Reticulum Haj; Fawaz G.; Verveer; Peter J.; Squire; Anthony; Neel; Benjamin G.; Bastiaens; Philippe I.H., Beth Israel Deaconess Medical Center, Science, 295(291), (2002)
Link To Paper

Abstract:
When bound by extracellular ligands receptor tyrosine kinases (RTKs) on the cell surfacetransmit critical signals to the cell interior. Although signal termination is less wellunderstood protein tyrosine phosphatase-1B (PTP1B) is implicated in the

Materials & Methods:
WT PTPIB was localized on ER membranes in growth factor—deprived cells [Fig. 1A; Web fig. 1 ( 1 13)]. PTP1BD/A also exhibited a reticular staining pattern that colocalized with the ER marker translocon-associated protein alpha (TRAP-a) in growth factor-deprived cells [Fig. 1B; Web fig. 1 ( 13)] ( 1). Thus inactivation of the PTP catalytic domain does not a priori alter PTP1B localization consistent with earlier work identifying the COOH-terminal hydrophobic domain as necessary and sufficient for ER localization ( 6). Within 15 rain of growth factor administration cells reconstituted with PTP1BD/A but not those reconstituted with WT PTP1B showed PTP1B immunoreactivity in discrete punctate structures that also immunostained with antibodies to TRAP-a [Fig. 1 C and D; Web fig. 1 ( 13)]. The majority of TRAP-a staining retained a reticular pattern under all conditions tested. Thus PTP1BD/A expression does not alter ER integrity after growth factor stimulation; instead PTP1BD/A appears to cluster in specific ER regions.

Microscopic Technique
Confocal Microscopy, Laser Scanning confocal Microscopy

Cell Type(s)
PTP1BD/A