TABLE 4.

Cell membrane accumulation of membrane or membrane-associated substrate candidatesa

ProteinMMPI/vehicle
MediumMembrane
RatioNo. of peptidesRatioNo. of peptides
Conditioned medium and membranes
    hnRNP E10.5121.662
    MMP-1b0.7121.531
    Chloride intracellular channel protein 10.7451.531
    Axl receptor tyrosine kinase0.2411.451
    RCC2 protein0.5711.391
    uPARb0.5811.361
    hnRNP R0.6931.293
    Multifunctional protein ADE20.7121.281
    CD590.4121.142
Membranes only
    Catechol O-methyltransferase1.732
    SERCA21.712
    Coatomer subunit1.621
    VDAC-21.611
    Myoferlin1.291
    Na+/K+-transporting ATPase α-4 chain1.271
    Integrin α3b1.174
Conditioned medium only
    TNF receptor superfamily member 12A0.311
    CD166 (ALCAM0.611
    Melanotransferrin0.751
  • a Proteins with increased ICAT ratios in the membrane fraction (Membrane) of MMP-14-transfected MDA-MB-231 cells and known membrane proteins with ratios decreased in the conditioned medium (Medium) in the presence of the inhibitor are implicated as being shed by metalloproteinases (MMPI/vehicle). Also shown are (i) membranes only, i.e., membrane proteins increased in the presence of MMPI, although peptides were not detected in the conditioned medium, and (ii) conditioned medium only, i.e., peptides for ectodomains of membrane proteins that showed decreases in conditioned medium but were not detected in the membrane preparation. Peptides were identified at ≥99% confidence, unless otherwise noted in Tables S1 and S2 in the supplemental material. Values shown are averages of all the peptide ratios quantified for each experiment. The individual peptide sequences are shown in Table S7 in the supplemental material. Abbreviations: hnRNP, heterogeneous nuclear ribonucleoprotein; SERCA2, sarcoplasmic/endoplasmic reticulum calcium ATPase 2; VDAC-2, voltage-dependent anion-selective channel protein 2; TNF, tumor necrosis factor; ALCAM, activated leukocyte cell adhesion molecule.

  • b Known substrate.