JAG1
protein-coding gene in the species Homo sapiens
Jagged1 (JAG1) is one of five cell surface proteins (ligands) that interact with four receptors in the mammalian Notch signaling pathway. The Notch signaling pathway is a highly conserved pathway that functions to establish and regulate cell fate decisions in many organ systems. Once the JAG1-NOTCH (receptor-ligand) interactions take place, a cascade of proteolytic cleavages is triggered resulting in activation of the transcription for downstream target genes. Located on human chromosome 20, the JAG1 gene is expressed in multiple organ systems in the body and causes the autosomal dominant disorder Alagille syndrome (ALGS) resulting from loss of function mutations within the gene. JAG1 has also been designated as CD339 (cluster of differentiation 339).
Structure and function
JAG1 was first identified as a ligand that was able to activate notch receptors when the rat gene Jagged encoding a protein homolog was cloned in 1995. The structure of the JAG1 protein includes a small intracellular component, a transmembrane motif, proceeded by an extracellular region containing a cystine-rich region, 16 EGF-like repeats, a DSL domain, and finally a signal peptide totaling 1218 amino acids in length over 26 coding exons.
The JAG1 protein encoded by JAG1 is the human homolog of the Drosophila jagged protein. Human JAG1 is one of five ligands for receptors in the NOTCH signaling pathway which helps to determine cellular fate and is active during many developmental stages. The extracellular component of the JAG1 protein physically interacts with its respective Notch receptor.
The public source identifies “JAG1” as protein-coding gene in the species Homo sapiens. This brief keeps that definition visible, then builds a research path around JAG1, protein-coding and gene.
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The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated May 4, 2026. The linked authority identifier is Q18251749. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1995 and 1218.
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This entry incorporates text from “JAG1” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.