Figure 6

αIIbβ3 integrin is enriched in compartments of Strumpellin-deficient platelets that share marker proteins with early endosomes, Golgi apparatus and the endoplasmic reticulum. (a) Workflow of the platelet granules preparation and immunomagnetic sorting of αIIbβ3-positive granules with subsequent quantitative mass spectrometric analysis. (b) Quantitative mass spectrometry analysis of 2524 unique polypeptides from Strumpellin-deficient vs. control sample (for one sample platelets of 5 mice were pooled). Significant enrichment of unique polypeptides in the Strumpellin-deficient sample (green + 2 and red + 1 data points on the right side of the volcano blot) and significant reduction of unique polypeptides in the Strumpellin-deficient sample (green − 2 and red − 1 data points on the left side of the volcano blot) are depicted as well as polypeptides that were present in a similar quantity in both samples (0, grey data points). The experiment in (b) was performed once. (c) Distribution of the 2524 common polypeptides in control and Strumpellin-deficient samples. 138 unique polypeptides were reduced in the Strumpellin-deficient sample and 164 unique polypeptides were enriched in the Strumpellin-deficient sample. 2222 unique polypeptides were present in a similar quantity in both samples. (d) Databank analysis of the GOCC terms of the enriched and reduced unique polypeptides. From the 164 enriched polypeptides 33 were associated with the endoplasmic reticulum (ER), 21 with the Golgi apparatus, 19 with mitochondria (Mito), 7 with early endosomes (Ee), 4 with late endosomes (Le), 2 with lysosomes (Lys), 10 with the cytoskeleton (Cyt) and 31 with the plasma membrane (Pm). From the 138 decreased polypeptides 13 were associated with the endoplasmic reticulum, 16 with the Golgi apparatus, 17 with mitochondria, 1 with early endosomes, 4 with late endosomes, 5 with lysosomes, 13 with the cytoskeleton and 31 with the plasma membrane.