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Rat Egfr (UniProt G3V6K6) is the canonical EGFR/ErbB1: a single-pass
transmembrane receptor tyrosine kinase with an extracellular ligand-binding
region of cysteine-rich subdomains, a transmembrane helix, and an intracellular
tyrosine kinase domain with a C-terminal phosphotyrosine tail for adaptor docking.
"EGFR is a single-pass transmembrane receptor with an extracellular ligand-binding region containing cysteine-rich subdomains, a transmembrane helix, and an intracellular tyrosine kinase domain with a C-terminal phosphotyrosine tail for adaptor docking."
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EGFR is a receptor protein-tyrosine kinase whose intrinsic kinase activity
increases upon ligand-induced dimerization, catalyzing autophosphorylation of
cytoplasmic tyrosines that generate SH2/PTB docking sites for GRB2, GAB1 and PLCgamma.
"EGFR is a **receptor protein-tyrosine kinase** that increases intrinsic kinase activity upon ligand-induced dimerization and catalyzes autophosphorylation on cytoplasmic tyrosines, generating SH2/PTB docking sites for signaling proteins such as GRB2, GAB1, and PLCĪ³."
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Ligand binding to the extracellular domain stabilizes an active conformation,
exposes a dimerization interface, and promotes receptor dimerization - the
obligatory activation mechanism.
"EGFR is activated by binding EGF-family ligands, which stabilizes an active extracellular conformation, exposes a dimerization interface, and promotes receptor dimerization."
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Core downstream outputs of EGFR are the RAS-RAF-MEK-ERK (MAPK), PI3K-AKT-mTOR,
and PLCgamma/IP3-Ca2+ signaling pathways.
"Core downstream outputs are **RAS-RAF-MEK-ERK**, **PI3K-AKT-mTOR**, and **PLCĪ³/IP3-Ca2+** signaling."
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EGFR functions primarily at the plasma membrane (extracellular ligand binding,
intracellular kinase signaling) and is internalized after activation.
"EGFR is primarily a **plasma-membrane** receptor (ligand binding outside the cell; kinase signaling inside), and it is internalized after activation."
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In native rat inner medullary collecting duct, EGFR is localized to the
basolateral plasma membrane, consistent with epithelial polarity and paracrine
signaling.
"In native rat IMCD, EGFR is reported at the **basolateral plasma membrane**, consistent with epithelial polarity and paracrine signaling in the collecting duct."
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Activated EGFR undergoes clathrin-mediated endocytosis and can keep signaling
from early endosomes before recycling or lysosomal degradation, which shapes
signal duration.
"ligand-activated EGFR undergoes **clathrin-mediated endocytosis (CME)** and can remain signaling-competent in **early endosomes**, with downstream signaling outputs shaped by whether receptors are recycled versus targeted to lysosomal degradation."
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In native rat IMCD, EGF stimulation produces phosphoproteomic signatures
consistent with canonical ErbB signaling (Raf/MEK/ERK; PI3K-Akt; mTOR;
endocytosis networks), embedding rat Egfr in the conserved EGFR architecture.
"In native rat IMCD, EGF stimulation produces phosphoproteomic signatures consistent with canonical ErbB signaling (Raf/MEK/ERK; PI3K-Akt; mTOR; endocytosis-associated networks), indicating that rat Egfr is embedded in the conserved EGFR signaling architecture in intact epithelial tissue."
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EGFR signaling is downregulated by Cbl-family E3 ubiquitin ligases acting
non-redundantly: Cbl-b preferentially engages EGFR via pY1045 while Cbl relies
on a GRB2-dependent mechanism.
"Cbl-b preferentially engages EGFR via **pY1045**, whereas Cbl relies more strongly on a **GRB2-dependent** mechanism."