EGFlike

EGFlike refers to proteins and protein domains that contain epidermal growth factor (EGF)-like repeats. These are small extracellular domains of about 40 amino acids that are characterized by a conserved set of cysteine residues that form three or more disulfide bonds. Some EGF-like repeats are calcium-binding (cbEGF) domains and rely on bound calcium for stability. In many proteins, EGF-like repeats occur in tandem and function as modular interaction surfaces.

EGFlike domains are widely distributed in metazoan extracellular proteins, including cell surface receptors, extracellular matrix components, and secreted factors. Notable examples include the extracellular portion of Notch, laminin, fibrillin, and some LDL receptor family proteins. The repeats often mediate protein–protein interactions and can influence proteolytic processing, receptor activation, or ligand presentation, contributing to signaling pathways such as Notch signaling and development.

From an evolutionary perspective, EGF-like repeats are a modular domain that has been shuffled between proteins, leading to diverse architectures. Bioinformatics tools identify them via characteristic cysteine patterns and motif signatures found in databases like Pfam and SMART.

In research, distinguishing EGFlike domains from EGF ligands is important because while they share the EGF-like motif, their roles differ: ligands typically activate receptors; repeats mediate structural or binding functions within larger proteins. Analysis of EGFlike domains informs protein structure, function, and evolutionary history.