THE HUMAN PROTEIN ATLAS BLOG
Image of the week - Polarized HEP G2 membrane
Welcome to the second edition of image of the week. This week's image was brought to us by citizen scientists in Project Discovery. After analyzing the recent data from the project, this image was among the most frequently labeled as "abnormal" by the users.
This is an image of EPB41L1 (erythrocyte membrane protein band 4.1-like 1). This staining is observed in HEP G2 human liver hepatocellular carcinoma cells. As you can clearly see here, there is significant cell-to-cell variation (CCD) in the staining, and even within a single cell at times.
As the name suggests, this is a well known membrane protein. In other cell lines seen on the atlas, EPB41L1 is also observed in the membrane, but appears much more uniformly across the cell samples.
To understand what makes this sample special we need to learn a little about the HEP G2 cell line. HEP G2 is a polarized cell line, meaning that apical (outward facing) and basolateral (inward facing) membranes behave (van IJzendoorn et al. 1997). This differential expression can be observed both in specific cells within cell clusters, and basolateral membranes within the cell cluster.
In this sample, we also observe basal aggregates of proteins within the sample. These could be aggresomes, however they appear to be outside the cell. They may be membrane aggregates created during the fixation process, but are more likely artifacts from the staining as we do not observe such aggregates in other images from this experiment (HEP G2 on the atlas link above).
We would like to again thank all the participants of Project Discovery for their contribution to science!