Endosome structures are intracellular sorting organelles involved in trafficking proteins within the cell. Here we describe fluorescent fusion proteins that can be used to identify early and late endosomes in live cells.
Endosomes are intracellular sorting organelles that transport subcellular components such as proteins and lipids from the Golgi . Proteins can also be internalized through the plasma membrane in a process known as endocytosis, pinocytosis, and phagocytosis . Learn more about these processes here. Endosomes are classified as early or late based on their stage following the internalization of cellular components. They are also distinguished by their morphology and Rab marker. Early endosomes are commonly formed near the plasma membrane and are distinguished by the Rab5A marker. Late endosomes mature from early endosomes and are distinguished by the Rab7A marker.
|Early endosome stains||Late endosome stains|
Stable signal from fluorescent protein targeted to the specific stage of endocytosis
|Common filter set|
CellLight fluorescent fusion proteins are ready-to-use constructs that label endosomes in live cells to follow the dynamics of intracellular behavior. CellLight Early Endosome labels use the Rab5a construct fused to emGFP (Figure 1) or TagRFP (Figure 2) while CellLight Late Endosome labels use the Rab7a construct fused to emGFP (Figure 3) or TagRFP (Figure 4).
Introducing CellLight fluorescent fusion proteins involves a simple transfection step using the BacMam technology, and they work like cell stains with minimal toxicity or chemical disruption. These endosome fusion proteins are compatible with other fluorescent probes for multiplex analysis in live cells, or after formaldehyde fixation for colocalization studies.
Figure 4. Late endosome-RFP co-localization with LysoTracker Deep Red. HeLa cells expressing CellLight Tubulin-GFP and CellLight Late Endsome-RFP was loaded with 50 nM LysoTracker Deep Red and Hoechst 33342. Images were pseudo colored as Hoechst 33342 (magenta), LysoTracker Deep Red (blue), CellLight Tubulin-GFP (green), and CellLight Late Endsome-RFP (red).
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