PT - JOURNAL ARTICLE AU - Jason A. Bush AU - Hideki Kitaura AU - Yuliang Ma AU - Steven L. Teitelbaum AU - F. Patrick Ross AU - Jeffrey W. Smith TI - Comparative Proteomic Analysis of a Cytosolic Fraction from β3 Integrin-deficient Cells DP - 2012 Jan 01 TA - Cancer Genomics - Proteomics PG - 1--13 VI - 9 IP - 1 4099 - http://cgp.iiarjournals.org/content/9/1/1.short 4100 - http://cgp.iiarjournals.org/content/9/1/1.full SO - Cancer Genomics Proteomics2012 Jan 01; 9 AB - Integrins are heterodimeric transmembrane receptors involved in sensing and transmitting informational cues from the extracellular environment to the cell. This study explored sub-proteome changes in response to elimination of the β3 integrin using a knockout murine model. Cleavable isotope-coded affinity tagging (cICAT) in combination with sub-cellular fractionation, multiple dimensions of separation and tandem mass spectrometry (MS/MS) were used to characterize differentially expressed proteins among β3 integrin–/– (β3–/–) mouse embryonic fibroblasts and isogenic wild-type (WT) controls. From a cytosolic protein fraction, 48 proteins were identified, in which expression differed by >1.5-fold. Predominant ontological groups included actin-binding/cytoskeletal proteins and protease/protease inhibitors. Interestingly, β3 integrin expression was inversely correlated with expression of cathepsin B, a lysosomal cysteine protease, as its expression was greater by over 3.5-fold in the β3–/– cells. This inverse correlation was also observed in stable heterologous cells transfected with β3 integrin, where the intracellular expression and activity of cathepsin B was lower compared to control cells. Our data suggests that the composition of the cellular proteome is influenced by integrin expression patterns and reveals a strong functional relationship between β3 integrin and cathepsin B.