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. 2009 Oct 6;106(40):17211–17216. doi: 10.1073/pnas.0904092106

Fig. 1.

Fig. 1.

Proteomic analysis of GCPs and adult synaptosomes. (A) Electron micrograph of GCPs. The GCP fraction was prepared by using the method described by Gordon-Weeks (14) (see SI Text). The criterion for a GCP was a particle with a diameter of ≈1–2 μm and the presence of small clear vesicles. (Scale bar: 10 μm.) (B) GCP proteins and proteins found in a membrane subfraction of GCP (GCM). In total, 629 GCP and 592 GCM proteins were identified, with 276 proteins common to both. Note that 316 proteins were identified only in the GCM subfraction. (C) Comparison of the GCP/GCM proteome with the proteome of adult synaptosomes. A total of 1,407 synaptosomal proteins were identified, for about twice as many as were identified in GCP or GCM. (D) Categorization of GCP, GCM, and synaptosomal proteins. Categories are color-coded as follows: metabolic enzymes, violet; cytoskeletal proteins, navy; signaling (except GTP-binding or phosphorylation), blue; proteins involved in guanine nucleotide cycling (including GTP-binding proteins), cyan; ion transport/channels, green; membrane traffic, lime; kinases or phosphatases, yellow; receptors, orange; chaperone, brown; proteasome/ubiquitination-related proteins, maroon; cell adhesion proteins, red; ribosomal, magenta; proteins involved in translation, olive; miscellaneous proteins (including organelle-specific or undefined), gray. Note that the ratio of cell adhesion molecules, receptors, and transporters/channels is higher in GCM than in GCP, consistent with enrichment of membrane components in GCM. See Table S1, Table S2, and Table S3 for a detailed report. (E) The major proteins of GCP or GCM as compared with synaptosomal proteins as indicated by the number of identified peptides. Among proteins for which 12 or more peptides were identified, we chose the subset identified as peptides at least twice as many times in GCP or in GCM than in synaptosomes. The number of peptide identifications is shown. (Upper) GCP > GCM. (Lower) GCM > GCP. Color-coded by functional category as in D. Note that the number of identified peptides is an indicator of relative protein levels.