THE HUMAN PROTEIN ATLAS BLOG
This week, it is Mitochondrial Disease Awareness Week. Therefore we would like to take the opportunity to talk about the mitochondrial proteome, the work we do within this field, and you will even get to meet one of our researchers, involved in this work.
The mitochondria are distributed throughout the cytoplasm of the cell, each organelle enclosed by a double membrane, the inner one forming the characteristic folds known as cristae. Mitochondria are essential for producing the cell´s need of ATP through cellular respiration, but have also been shown to participate in many other cellular functions, including apoptosis, calcium storage and cellular signaling...Read more
Welcome to another HPA image of the week! This week we take a look at another member of the vesicle family, the lysosomes.
In a way, lysosomes can be thought of as the recycling plants of your cells. Lysosomes are small membrane bound vesicular organelles that degrade biomolecules within your cells so that the materials in these molecules can be recycled and used for other cellular processes. Often these biomolecules come from vesicles known as endosomes that bring in materials from outside your cells, however lysosomes are also known to degrade other organelles, and products from within the cell...Read more
Welcome back blog fans! After a brief hiatus the image of the week highlights from the HPA are back! This week we are discussing the Endoplasmic reticulum, which is not just difficult to say, but is where many of your proteins are made.
The endoplasmic reticulum (ER) is one of the largest organelles in the cell. It is a delicate membranous network composed of sheets and tubules that spreads throughout the whole cytoplasm and is actually contiguous to the nuclear membrane. Two major forms of the ER can be distinguished: the rough ER and the smooth ER. Both have different functions...Read more
Though frequently overlooked as being a "catch-all" for proteins that don't reside within another organelle, cytoplasmic proteins are anything but.
One important role of proteins in the cytoplasm is the regulation of gene expression. There are two main ways in which gene expression is regulated; when converting the genetic code in your DNA to RNA (transcription), and when converting RNA to proteins (translation). Though transcription (DNA to RNA) occurs in the nucleus, cytoplasmic proteins are often involved in activating transcription factors which then move to the nucleus to perform transcription.
The protein stained in Fig 1...Read more
Let's have a look at another fascinating compartment of the cell, the centrosome! Located in close proximity to the nucleus, the centrosome is so small that it sometimes suffers from being overlooked. However, despite its humble size it is a very important organelle with great impact on cellular function.
The centrosome was first described in 1888 and has been a very popular organelle to study among biology researchers ever since (Conduit P.T. 2015). The most well characterized function of the centrosome is to serve as the organizing center for the microtubules that build up the internal architecture of the cell, the so-called cytoskeleton...Read more
It's time for another Image of the week! This week's image is brought to us by Diana Mahdessian, who works on the Subcellular protein atlas, and highlights cell division and various stages of mitosis. In previous blogs we have discussed the importance of certain proteins in the cell cycle including dividing centrosomes and FDXR in mitochondria.
The cell cycle is an ordered series of events that ultimately leads to the division of the "mother" cell into two "daughter" cells (cells are given feminine names because they are capable of reproducing).
The cell cycle consists of three distinct phases; interphase, mitosis and cytokinesis...Read more
Welcome back to HPA image of the week! This week we highlight another organelle brought to us by Mikaela Wiking aka HPA_Illuminator, the intermediate filaments!
Intermediate filaments are one of the three cytoskeletons of the cell, together with actin filaments and microtubules.
The expression of intermediate filaments can be extremely dependent on cell type, for example the intermediate filament protein group keratins, discussed in a previous IOTW, are key components in hair, nails and skin...Read more
Welcome back to Image of The Week! We will be periodically highlighting an organelle in the coming image of the week posts, written by members of the Subcellular Human Protein Atlas project. This week we kick things off with a post by HPA_Illuminator, and what better way to start than with the mitochondria, the (true) powerhouse of the cell!!!
Mitochondria are found in almost all human cells, in varying numbers. They are known as the powerhouse of the cell as they are responsible for producing the majority of the energy in your body (in the form of ATP, adenosine triphosphate)...Read more
Welcome to HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by solartech0 who found this image while playing Project Discovery in EVE online.
The protein stained in Fig 1. is an image of ferredoxin reductase (FDXR) found in the mitochondria of the cell. This sample shows a staining of FDXR in A549 adenocarcinomic alveolar basal epithelial cells.
FDXR is a protein involved in cellular metabolism. This process is what provides energy for our cells and is carried out in the mitochondria of the cell...Read more
It's time for another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by x Truf a member of the Signal Cartel in EVE online who found this image while playing Project Discovery.
The protein stained in Fig 1. is an image of Moesin (MSN) found in the plasma membrane of the cell. This sample shows a staining of MSN in U-251 MG human glioblastoma astrocytoma (brain) cells.
MSN is a member of the ERM family which provide a link between plasma membranes and actin filaments. This link was briefly discussed in a previous blog...Read more
Welcome to another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Shiverwarp who found this image while playing Project Discovery in EVE online.
The protein stained in Fig 1. is an image of Coronin, actin binding protein, 2B (CORO2B) found in the focal adhesions and at the plasma membrane of the cell. This sample shows U-251 MG human glioblastoma astrocytoma (brain) cells.
Focal adhesions are transmembrane groups of protein that allow the cell to "grab" the surrounding environment...Read more
Welcome to another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Selphentine who pointed out several nice examples of proteins localized to "nuclear speckles". In Project Discovery, citizen scientists are refining our annotations for proteins within the nucleus by labeling these nuclear speckles, previously not annotated in the atlas.
The protein stained in Fig 1. is an image of DEAD (Asp-Glu-Ala-Asp) box polypeptide 39B (DDX39B) seen in the nuclear speckles. This sample shows MCF-7 cells, a human adenocarcinoma cell line from breast cancer...Read more
This week HPA image of the week, I've decided to highlight two of my favorite things, the cell cycle and actin filaments!
The protein labeled in Fig 1. is an image of Cell division cycle 42 effector protein (Rho GTPase binding) 4 (CDC42EP4). In addition to being quite a mouthful, this protein resides in the cytoplasm and is associated with the actin filaments. In this image, CDC42EP4 is seen in U-2 OS human osteosarcoma cells.
As the name suggests, the CDC42EP4 is a protein associated with CDC42, which helps regulate the transition from G1 to S (in which DNA is replicated), and is essential for proper cell cycle progression (Yasuda S et al. 2006)...Read more
It's the end of the week, and that means another HPA image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Aleksandra Shaishi who found this image playing Project Discovery.
The protein labeled in Fig 1. is an image of the antibody HPA006539, which labels solute carrier family 2 (facilitated glucose transporter) (SLC2A) member 3 and member 14. This is what we call a "multi-targeting" antibody as it binds more than one protein...Read more
It's time for another Image of the week! This week's image was brought to us by citizen scientists in Project Discovery, and specifically by Yadaryon who pointed out several nice examples of proteins localized to the rim of the nucleoli.
The nucleolus is an organelle within the nucleus of your cells. There may be one or more nucleoli in each nucleus, but they usually occur in small numbers. The primary job of the nucleoli is to assemble ribosomes which in turn make proteins within your cells...Read more
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...Read more
Introducing the HPA image of the week! Each week we will pick an image we find particularly interesting and briefly discuss it. This series will particularly focus on images brought to us by citizen scientists working on Project Discovery, though may include images from other projects in the atlas as well.
This week's image is brought to us by citizen scientist CalebAyrania who found this staining playing Project Discovery and correctly identified the antibody as labeling centrosomes in mitotic cells (cells undergoing division). This staining was observed in CACO-2 colorectal epithelial adenocarcinoma cells...Read more
Systematic antibody validation with siRNA for the Human Protein Atlas
Antibodies are among the most frequently used tools for basic research and clinical assays. For antibodies used in therapy or diagnostics, there are well-defined and strict guidelines that must be complied with before approval for clinical assays. For research antibodies, such guidelines have not yet been developed, despite the importance of demonstrating that they are specific, selective, and yield reproducible results in the immunoassay for which they are to be used...Read more
Version 14 of The Human Protein Atlas includes a new type of validation of antibodies that are used for determining the subcellular localization of a protein.
A set of antibodies have been analyzed in transgenic cell lines expressing GFP-tagged target protein at near-endogenous levels to confirm that the antibodies are capable of binding the target protein. The approved antibodies are then used to determine the subcellular localization of endogenous protein in a selection of cell lines. A high validation score is assigned to those genes where the same location(s) are observed for both tagged protein and protein detected using labelled antibody in non-transfected cells...Read more
Immunofluorescence and fluorescent-protein tagging show high correlation for protein localization in mammalian cells
The Human Protein Atlas applies antibodies for a variety of applications to map protein expression in different tissues and also at the subcellular level. Within the subcellular protein atlas, immunofluorescence (IF) is used to uncover the localization of proteins to different organelles. To ensure an accurate localization of each and very protein, the antibodies have to be specific to their target protein...Read more