The membrane proteome of the mouse lens fiber cell.
OBJECTIVE
Fiber cells of the ocular lens are bounded by a highly specialized plasma membrane. Despite the pivotal role that membrane proteins play in the physiology and pathophysiology of the lens, our knowledge of the structure and composition of the fiber cell plasma membrane remains fragmentary. In the current study, we utilized mass spectrometry-based shotgun proteomics to provide a comprehensive survey of the mouse lens fiber cell membrane proteome.


METHODS
Membranes were purified from young mouse lenses and subjected to MudPIT (Multidimensional protein identification technology) analysis. The resulting proteomic data were analyzed further by reference to publically available microarray databases.


RESULTS
More than 200 membrane proteins were identified by MudPIT, including Type I, Type II, Type III (multi-pass), lipid-anchored, and GPI-anchored membrane proteins, in addition to membrane-associated cytoskeletal elements and extracellular matrix components. The membrane proteins of highest apparent abundance included Mip, Lim2, and the lens-specific connexin proteins Gja3, Gja8, and Gje1. Significantly, many proteins previously unsuspected in the lens were also detected, including proteins with roles in cell adhesion, solute transport, and cell signaling.


CONCLUSIONS
The MudPIT technique constitutes a powerful technique for the analysis of the lens membrane proteome and provides valuable insights into the composition of the lens fiber cell unit membrane.
Bassnett
Steven
S
Ophthalmology & Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA. Bassnett@vision.wustl.edu
Wilmarth
Phillip A
PA
David
Larry L
LL
D000818:Animals; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D016623:Ion Pumps / Q000378:metabolism; D007908:Lens, Crystalline / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D020543:Proteome / Q000378:metabolism*; D015398:Signal Transduction; D018631:ras Proteins / Q000378:metabolism
D007473:Ion Channels; D016623:Ion Pumps; D020543:Proteome; D018631:ras Proteins