LDLRAD2

Model summary

A single-pass cell-surface receptor-like protein that presents a modular extracellular recognition platform to bind extracellular ligands and matrix components, thereby organizing signaling pathways that guide neuronal maturation. Its ectodomain architecture enables high-avidity ligand capture and clustering at the plasma membrane, which in turn recruits intracellular adaptors to influence neurite outgrowth and differentiation.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The sequence is encompassed by IPR042333 (LRAD2/Mig-13-like family, residues 1–224), marking it as a member of the LRAD/Mig-13-like receptor family that typically functions as a single-pass membrane protein with an extracellular recognition module. The N-terminal ectodomain contains IPR035914 (Spermadhesin, CUB domain superfamily, residues 30–173), a β-sandwich module widely used for extracellular ligand capture and adhesion. Immediately downstream sits an LDL receptor-like module: IPR036055 (LDL receptor-like superfamily, residues 173–215) and, within it, IPR002172 (LDL receptor class A repeat, residues 172–215). The CUB domain followed by a calcium-binding LDLR class A repeat creates a tandem recognition platform that binds extracellular ligands and matrix components with high avidity. This ectodomain arrangement precedes a single-pass transmembrane segment and short cytosolic tail typical of LRAD/Mig-13-like proteins, consistent with a membrane-embedded signaling receptor.

2. 02

   This extracellular CUB–LDLR repeat architecture dictates molecular function as protein binding (GO:0005515).

   CUB domains provide broad-spectrum binding to extracellular proteins and proteoglycans, while LDLR class A repeats stabilize calcium-dependent complexes and frequently mediate endocytic or signaling receptor interactions. The LRAD2/Mig-13-like family signature indicates that binding events at the cell surface are transduced across the membrane, supporting a receptor-like role that organizes downstream pathways through protein–protein interactions rather than enzymatic catalysis.

3. 03

   From this binding-centric receptor mechanism, the biological process follows.

   LRAD/Mig-13-like receptors are expressed in neural contexts and modulate neuronal lineage decisions. A cell-surface recognition module that tunes adhesion and matrix cues causally influences neurite outgrowth and fate acquisition, aligning with neuron differentiation (GO:0030182). The tandem CUB–LDLR ectodomain is well-suited to interpret extracellular morphogens and adhesion cues that guide neuronal maturation.

4. 04

   The cellular component is dictated by the single-pass topology and LRAD family identity.

   The presence of an extensive extracellular ectodomain coupled to a transmembrane core places the protein in membrane (GO:0016020). The architecture and single-pass annotation indicate a cell-surface receptor embedded in the plasma membrane, where it can survey extracellular ligands and relay signals to the cytosol.

5. 05

   Mechanistically, the ectodomain captures extracellular ligands via the CUB domain and calcium-stabilized LDLR repeats, clustering the receptor and triggering intracellular signaling through its cytosolic tail.

   This likely recruits adaptor proteins and cytoskeletal regulators that steer neuronal differentiation. I hypothesize that it forms complexes with extracellular matrix components and cell-surface co-receptors, and intracellularly associates with endocytic and signaling adaptors to modulate neurite patterning and maturation.