ExoCarta: A compendium of exosomal proteins and RNA

TLDR

Exosomes are 40–100 nm membrane vesicles secreted by most cell types, traditionally characterized by electron microscopy and a set of conserved marker proteins such as Alix, CD9, and CD63, though tissue‑specific proteins can alter marker presence. The authors created ExoCarta, a freely accessible compendium of exosomal proteins and RNA that enables researchers to identify common markers and tissue‑specific proteins for immunoaffinity isolation and future analyses. ExoCarta aggregates proteins and RNA molecules identified in exosomes from diverse studies, providing a searchable database for the scientific community. ExoCarta is the first resource of its kind and is available online at http://exocarta.ludwig.edu.au.

Abstract

Exosomes, membrane microvesicles (40-100 nm) secreted by most cell types, can be isolated in several ways while characterizing them is heavily based on electron microscopy and, most importantly, the identification of exosome marker proteins. Researchers rely on the identification of certain exosomal marker proteins including Alix, CD9 and CD63 to confirm the presence of exosomes in their preparations. An evolutionary-conserved set of protein molecules have been identified in most exosomes studied to date. However, with the complexity of tissue/cell type-specific proteins being incorporated in the exosomes, some of these so-called exosomal markers are not always present in all the exosomes. The presence of tissue/cell type-specific proteins in exosomes allows researchers to isolate them using immunoaffinity capture methods. A compendium for exosomal proteomes will aid researchers in identifying proteins that were more commonly found in various exosomes (exosome markers) and those that are specific to certain tissue/cell type-derived exosomes. Here, we describe ExoCarta, a compendium for proteins and RNA molecules identified in exosomes. ExoCarta is first of its kind and the resource is freely available to the scientific community through the web (http://exocarta.ludwig.edu.au). We believe that this community resource will be of great biological importance for any future exosome analyses.