Table 1 Mass spectrometry analysis of exosomes purified from human CSF or from the supernatant of transfected rat choroid plexus Z310 cells.

From: Choroid plexus transcytosis and exosome shuttling deliver folate into brain parenchyma

Human CSF

Z310 vector-transfected

Z310 FRα-transfected

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)

ALG-2 interacting protein X (Alix)

ALG-2 interacting protein X (Alix)

ALG-2 interacting protein X (Alix)

Flotillin-1

Flotillin-1

Flotillin-1

Flotillin-2

Flotillin-2

Flotillin-2

Folate receptor α

—

Folate receptor α (human)

Tumour suspectibility gene 101 (TSG101)

Tumour suspectibility gene 101 (TSG101)

Tumour suspectibility gene 101 (TSG101)

C-1-tetrahydrofolate synthase

C-1-tetrahydrofolate synthase

C-1-tetrahydrofolate synthase

CD63

CD63

CD63

Transferrin receptor protein (CD71)

Transferrin receptor protein (CD71)

Transferrin receptor protein (CD71)

  1. Exosome preparations from human CSF and Z310 cells were analysed by mass spectrometry. Each preparation contained a couple of hundred proteins with a high probability of over 95%. Among these we could identify FRα in the sample derived from human CSF as well as in FRα-transfected Z310 cells. Although expression of endogenous rat FRα in Z310 cells has previously been indicated by RT–PCR23, the rat FRα expression might be under the mass spectrometric detection level. Exosomal markers like ALG-2 interacting protein X (Alix), flotillin-1 (Flot-1), flotillin-2 (Flot-2), CD63, tumour susceptibility gene 101 (TSG101) and transferrin receptor (CD71) could consistently be detected in all exosome preparations, indicating a similar composition of exosomes derived from Z310 cells when compared with exosomes purified from human CSF. The order in Supplementary Table S1 represents semiquantitative incidence of proteins determined by the ranking of unweighted spectrum counts in the program Scaffold 3. Taking the 25 most frequently identified proteins in exosomes (http://exocarta.org/exosome_markers)22, we found 22 (88%) in human CSF and 21 (84%) in the supernatant of Z310 cells, respectively.
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