The key difference between STAT5A and STAT5B is that STAT5A is a protein in humans coded by STAT5A gene while STAT5B is a protein in humans coded by STAT5B gene.
Signal transducer and activator of transcription (STAT) is a family of universal transcription factors. They are proteins that help cells to sense and respond to environmental changes. They mediate cellular responses to various cytokines and hormones. They mainly regulate the expression of genes in multiple cell types. There are seven types of STAT proteins. Among them, STAT5 is a family containing two proteins that are highly related. They are STAT5A and STAT5B in humans and stat5a and stat5b in rodents. Human STAT5A and STAT5B show more than 90% of peptide sequence similarity. Therefore, they structurally differ only by 6 amino acids in their DNA binding domains, 20 amino acids in their C-termini and 18 amino acids in their N-termini. STAT5 proteins get activated during the earliest signalling events mediated by IL-2 family of cytokines. This allows the fast delivery of signals from membrane to nucleus in order for gene expression.
CONTENTS
1. Overview and Key Difference
2. What is STAT5A
3. What is STAT5B
4. Similarities Between STAT5A and STAT5B
5. Side by Side Comparison – STAT5A vs STAT5B in Tabular Form
6. Summary
What is STAT5A?
STAT5A is a protein in humans coded by the gene SATA5A. It is one of the two closely related proteins of STAT5. STAT5A has six membrane domains or functional units. Other than six functional domains, there are a few specific amino acids that contribute to the STAT5A. It differs from STAT5B from a few numbers of amino acids.
Figure 01: STAT5A
STAT5A mediates the responses of many cell ligands such as IL2, IL3, IL7 GM-CSF, erythropoietin, thrombopoietin, and different growth hormones, etc. The deficiency of STAT5A leads to several diseases such as chronic leukemia and myeloproliferative neoplasm.
What is STAT5B?
STAT5B is the second closely related protein in STAT5 family. It is a transcription factor. It is coded by STAT5B gene in humans. This protein mediates the signal transduction of various cell ligands such as IL2, IL4, CSF1, and different growth hormones, etc.
Figure 02: STAT5B
Moreover, STAT5B participates in TCR signalling, apoptosis, adult mammary gland development, and sexual dimorphism of liver gene expression. STAT5B plays biological roles in allergic disease, immunodeficiencies, autoimmunities, cancers, hematological disease, growth disorders, and lung disease.
What are the Similarities Between STAT5A and STAT5B?
- STAT5A and STAT5B are universal transcription factors.
- They are fraternal twins of signal transduction and transcriptional activation.
- They are two highly related monomeric proteins
- Structurally, they show peptide sequence similarities greater than 90%.
- Both proteins could bind to the same targets.
- They mediate signals for a broad spectrum of cytokines and tyrosine kinase receptors.
- They regulate the expression of the target genes in a cytokine-specific fashion.
- Both STAT5A and STAT5B are essential for the normal development of all lymphoid lineages.
- Two genes that code for STAT5A and STAT5B are collocated on 17q11.
- Their genes are regulated by an Sp-1 cis-element.
What is the Difference Between STAT5A and STAT5B?
The gene STAT5A codes for the protein STAT5A while the gene STAT5B codes for the protein STAT5B. So, this is the key difference between STAT5A and STAT5B. Moreover, STAT5A mediates the responses of many cell ligands, such as IL2, IL3, IL7 GM-CSF, erythropoietin, thrombopoietin, and different growth hormones, while STAT5B protein mediates the signal transduction triggered by various cell ligands, such as IL2, IL4, CSF1, and different growth hormones.
The below infographic summarizes the difference between STAT5A and STAT5B in tabular form.
Summary – STAT5A vs STAT5B
STAT5A and STAT5B are two closely related proteins which help in signal transduction and transcription activation. STAT5A gene codes for STAT5A while STAT5B gene codes for STAT5B. Both genes are collocated on 17q11 and they are regulated by an Sp-1 cis-element. Both proteins mediate the responses of cytokines and tyrosine kinase receptors. Thus, this is the summary of the difference between STAT5A and STAT5B.
Reference:
1. Kanai, Takahiro, et al. “Identification of STAT5A and STAT5B Target Genes in Human T Cells.” PloS One, Public Library of Science, 30 Jan. 2014, Available here.
2. “STAT5A.” Wikipedia, Wikimedia Foundation, 13 Dec. 2020, Available here.
Image Courtesy:
1. “Protein STAT5A PDB 1y1u” By Emw – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Protein STAT5B PDB 1y1u” By Emw – Own work (CC BY-SA 3.0) via Commons Wikimedia