Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be included within or excluded from the final, processed messenger RNA (mRNA) produced from that gene. This means the exons are joined in different combinations, leading to different (alternative) mRNA strands. Consequently, the proteins translated from alternatively spliced mRNAs usually contain differences in their amino acid sequence and, often, in their biological functions.
Titin is a protein that in humans is encoded by the TTN gene. Titin is a giant protein, greater than 1 µm in length, that functions as a molecular spring that is responsible for the passive elasticity of muscle. It comprises 244 individually folded protein domains connected by unstructured peptide sequences. These domains unfold when the protein is stretched and refold when the tension is removed.
RNA-binding proteins are proteins that bind to the double or single stranded RNA in cells and participate in forming ribonucleoprotein complexes. RBPs contain various structural motifs, such as RNA recognition motif (RRM), dsRNA binding domain, zinc finger and others. They are cytoplasmic and nuclear proteins. However, since most mature RNA is exported from the nucleus relatively quickly, most RBPs in the nucleus exist as complexes of protein and pre-mRNA called heterogeneous ribonucleoprotein particles (hnRNPs). RBPs have crucial roles in various cellular processes such as: cellular function, transport and localization. They especially play a major role in post-transcriptional control of RNAs, such as: splicing, polyadenylation, mRNA stabilization, mRNA localization and translation. Eukaryotic cells express diverse RBPs with unique RNA-binding activity and protein–protein interaction. According to the Eukaryotic RBP Database (EuRBPDB), there are 2961 genes encoding RBPs in humans. During evolution, the diversity of RBPs greatly increased with the increase in the number of introns. Diversity enabled eukaryotic cells to utilize RNA exons in various arrangements, giving rise to a unique RNP (ribonucleoprotein) for each RNA. Although RBPs have a crucial role in post-transcriptional regulation in gene expression, relatively few RBPs have been studied systematically.It has now become clear that RNA–RBP interactions play important roles in many biological processes among organisms.
In cellular biology, P-bodies, or processing bodies, are distinct foci formed by phase separation within the cytoplasm of a eukaryotic cell consisting of many enzymes involved in mRNA turnover. P-bodies are highly conserved structures and have been observed in somatic cells originating from vertebrates and invertebrates, plants and yeast. To date, P-bodies have been demonstrated to play fundamental roles in general mRNA decay, nonsense-mediated mRNA decay, adenylate-uridylate-rich element mediated mRNA decay, and microRNA (miRNA) induced mRNA silencing. Not all mRNAs which enter P-bodies are degraded, as it has been demonstrated that some mRNAs can exit P-bodies and re-initiate translation. Purification and sequencing of the mRNA from purified processing bodies showed that these mRNAs are largely translationally repressed upstream of translation initiation and are protected from 5' mRNA decay.
In cellular biology, stress granules are biomolecular condensates in the cytosol composed of proteins and RNAs that assemble into 0.1–2 μm membraneless organelles when the cell is under stress. The mRNA molecules found in stress granules are stalled translation pre-initiation complexes associated with 40S ribosomal subunits, translation initiation factors, poly(A)+ mRNAs and RNA-binding proteins (RBPs). While they are membraneless organelles, stress granules have been proposed to be associated with the endoplasmatic reticulum. There are also nuclear stress granules. This article is about the cytosolic variety.
Protein unc-13 homolog D, also known as munc13-4, is a protein that in humans is encoded by the UNC13D gene.
Tropomyosin alpha-3 chain is a protein that in humans is encoded by the TPM3 gene.
Ras GTPase-activating protein-binding protein 1 is an enzyme that in humans is encoded by the G3BP1 gene.
Nucleolysin TIAR is a protein that in humans is encoded by the TIAL1 gene.
Polyglutamine-binding protein 1 (PQBP1) is a protein that in humans is encoded by the PQBP1 gene.
TAR DNA-binding protein 43 is a protein that in humans is encoded by the TARDBP gene.
Double-stranded RNA-binding protein Staufen homolog 1 is a protein that in humans is encoded by the STAU1 gene.
The serine/threonine-protein kinase/endoribonuclease inositol-requiring enzyme 1 α (IRE1α) is an enzyme that in humans is encoded by the ERN1 gene.
RNA-binding motif 10 is a protein that is encoded by the RBM10 gene. This gene maps on the X chromosome at Xp11.23 in humans. RBM10 is a regulator of alternative splicing. Alternative splicing is a process associated with gene expression to produce multiple protein isoforms from a single gene, thereby creating functional diversity and cellular complexity. RBM10 influences the expression of many genes, participating in various cellular processes and pathways such as cell proliferation and apoptosis. Its mutations are associated with various human diseases such as TARP syndrome, an X-linked congenital disorder in males resulting in pre‐ or postnatal lethality, and various cancers in adults.
Fas-activated serine/threonine kinase is an enzyme that in humans is encoded by the FASTK gene.
Fox-1 homolog A, also known as ataxin 2-binding protein 1 (A2BP1) or hexaribonucleotide-binding protein 1 (HRNBP1) or RNA binding protein, fox-1 homolog (Rbfox1), is a protein that in humans is encoded by the RBFOX1 gene.
Messenger RNP is mRNA with bound proteins. mRNA does not exist "naked" in vivo but is always bound by various proteins while being synthesized, spliced, exported, and translated in the cytoplasm.
FAST kinase domain-containing protein 5 (FASTKD5) is a protein that in humans is encoded by the FASTKD5 gene on chromosome 20. This protein is part of the FASTKD family, which is known for regulating the energy balance of mitochondria under stress. FASTKD5 is also required for RNA granules to process precursor mRNAs not flanked by tRNAs.
Benjamin Wolozin is an American pharmacologist and neurologist currently at Boston University School of Medicine and an Elected Fellow of the American Association for the Advancement of Science. Benjamin Wolozin, M.D., Ph.D. received his B.A. from Wesleyan University and his M.D., Ph.D. from the Albert Einstein College of Medicine. He is currently a professor of Pharmacology, Neurology and the Program in Neuroscience at Boston University School of Medicine. He is also co-founder and Chief Scientific Officer (CSO) of Aquinnah Pharmaceuticals Inc., a biotechnology company developing novel therapeutics to treat Alzheimer's disease and Amyotrophic Lateral Sclerosis.
Nancy Kedersha is an American cell biologist and micrographer. She got her Ph.D. from Rutgers University where she worked in Richard Berg's lab studying the characteristics and assembly of prolyl hydroxylases. Afterwards she joined Leonard Rome's lab at UCLA as a post-doctoral fellow where she co-discovered the vault (organelle). Subsequently, she worked at ImmunoGen Inc. where she worked on staining and photographing different cancer cells. She then worked as an instructor of medicine at Brigham and Women's Hospital in Paul Anderson's lab, where her work focused on studying stress granule formation. In late-2020, she retired. In addition to her contributions as a scientist, Kedersha has been quite successful in different microscopy competitions. She is a four-time Nikon Small World finalist and in 2011 she won the Lennart Nilsson Award.
