Exploring Lung Proteins and Antibodies

Exploring Lung Proteins and Antibodies
For World Lung Cancer day, we take a closer look at the human lung specific proteome.
Which proteins are expressed in lung? Here we explore the Human Protein Atlas's analysis of
the lung specific transcriptome, and present selected antibodies against proteins specifically
expressed in lung and lung cancer. All antibodies are presented on the Human Protein Atlas
and available in our catalog as Triple A Polyclonals and PrecisA Monoclonals.
68% of all human proteins are expressed in lung
More than two thirds of all human proteins are expressed in lung. The number is based on the
Human Protein Atlas's analysis of RNA-Seq data for approximately 20,000 human proteins.
Only 20 lung specific (enriched) proteins
Of all the genes expressed in lung, 190 genes show various degrees of elevated expression in
lung compared to other tissues. Only 20 genes were found to be lung specific (enriched),
expressed at least five times more in lung as compared to other tissues 76% of the mRNA
produced in lung were found to correspond to housekeeping genes.
The SFTPA1 (Surfactant Protein A1) protein is tissue enriched in lung, with at least 5 times higher RNA expression in lung
compared to other tissues. This is illustrated here with IHC staining in seven different tissues using the Anti-SFTPA1
antibody (HPA045752). No staining is seen in cerebral cortex (A), colon (B), kidney (C), liver (D), lymph node (E) or testis
(F) tissues, whereas the Anti-SFTPA1 antibody staining in human lung shows strong positivity in pneuomocytes (G).

Lung enriched Proteins Relate to Gaseous Exchange, Cilium Movement
and Surfactant Homeostasis
The genes that show elevated expression in lung correspond to proteins expressed in
pneumocytes, macrophages and in ciliated, mucus secreting and endothelial cells of the lung.
Pneumocytes are essential for respiration by producing surfactant. Surfactant protein C is a
pneumocyte specific protein, detected by the Anti-SFTPC antibody in the image below.
Macrophages in lung play an important role in the defense against airborne microorganisms.
An example of a gene that is enriched in macrophages is the Mast Cell-Expressed Membrane
Protein 1, stained in the image below using the Anti-MCEMP1 antibody.
IHC staining using Anti-SFTPC antibody (HPA010928) in lung tissue shows distinct cytoplasmic
positivity in Type II pneumocytes.
In Western Blot, the Anti-SFTP antibody detects a predicted band of 21 kDa in lung tissue lysate.

IHC staining using Anti-MCMP1 antibody (HPA014731) shows strong positivity of macrophages in
human lung tissue.
The ciliated cells free the airways from contaminants. A protein enriched in ciliated cells is
the Deleted in Lung and Esophageal Cancer 1-protein DLEC1 that is detected with the Anti-
DLEC1 antibody in the image below.
Mucus maintains a suitable environment for ciliary function and protects against infections
agents. Uteroglobin is a protein expressed in mucus secreting cells. In the image below
uteroglobin is detected by the Anti-SCGB1A1 antibody.
The endothelial cells in the lung participates in gaseous exchange. ACE (Angiotensin I
converting enzyme) is an example of a protein expressed in the endothelial lung cells, here
shown using an Anti-ACE antibody.
IHC staining using Anti-DLEC1 antibody (HPA019077) shows strong positivity of cilia in human
fallopian tube tissue.

IHC staining using Anti-SCGB1A1 antibody (HPA031828) in human lung tissue shows positivity in
mucus secreting cells.
IHC staining using Anti-ACE antibody (HPA029298) in human lung tissue shows positivity in
endothelial cells.
Lung Cancer in The Cancer Atlas
In the Cancer Atlas on the Human Protein Atlas portal, all antibodies have been stained in 12
different lung cancer samples, as well as in samples from 19 other cancers.
The Anti-SFTPB antibody shows selective cytoplasmic expression in pneumocytes and in
occasional lung cancer samples, but not in other cancer forms. This is illustrated below
with an image from the Human Protein Atlas Cancer Atlas entry of the SFTPB protein.
Anti-SFTPB antibody (HPA062148) staining of cancer tissues, showing strong positivity in lung cancer, but no staining in
other cancers. Screenshot from the Human Protein Atlas SFTPB protein entry in the Cancer Atlas.

Staining Patterns Seen in Lung Cancer Samples
Strong membranous positivity in tumor cells in human lung cancer tissue using Anti-CTNNB1
antibody (HPA029159).
Strong cytoplasmic positivity in tumor cells in human lung cancer tissue using Anti-CLCA2 antibody
(HPA047192).
Strong nuclear positivity in tumor cells in human lung cancer tissue using Anti-FOXA1 antibody
(HPA050505).