RUNDC1

Model summary

A cytosolic adaptor that organizes small GTPase-centered signaling assemblies controlling adhesion and migration during embryonic tissue formation. Its internal scaffold region positions a C‑terminal RUN module that binds small GTPases and their effectors, enabling dynamic assembly of trafficking and cytoskeletal regulators. By tuning focal adhesion turnover and endocytic recycling, it supports migratory behavior of embryonic kidney cells and broader developmental programs within the cytoplasm.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   A central module, IPR058732 (RUN domain-containing protein 1, middle domain, residues 181–285), precedes a C‑terminal RUN system composed of IPR037213 (RUN domain superfamily, residues 376–610) and the embedded IPR004012 (RUN domain, residues 421–602). This linear arrangement—an internal scaffold-like “middle” region followed by a well-defined RUN fold—creates a bipartite adaptor: the middle domain likely stabilizes intramolecular or intermolecular assemblies, while the RUN domain provides a high-affinity platform for small GTPase recognition. RUN domains are structurally adapted to bind Ras-like small GTPases and their regulators; this architecture therefore causes selective small GTPase binding as the primary molecular function, aligning with GO:0031267 small GTPase binding.

2. 02

   From this molecular function, I infer the biological role.

   Small GTPase-binding adaptors typically tune membrane trafficking and cytoskeletal interfaces that govern cell polarity, adhesion, and migration. Such control points are repeatedly co-opted during tissue morphogenesis. Consequently, a RUN-driven signaling adaptor plausibly contributes to developmental programs, consistent with GO:0001701 in utero embryonic development. The explicit link to embryonic kidney cell migration and adhesion fits this logic: RUN-mediated assemblies can steer focal adhesion turnover and endocytic recycling, which together shape migratory behavior and epithelial patterning.

3. 03

   Cellular placement follows from the soluble adaptor nature of RUN modules and the absence of transmembrane features.

   The protein’s soluble architecture and assembly-prone regions support a cytosolic residence, consistent with GO:0005829 cytosol and the broader cytoplasmic designation. A cytosolic pool can dynamically sample membrane-proximal signaling hubs via transient complexes.

4. 04

   Mechanistically, the middle domain (181–285) likely nucleates complex formation and positions the RUN core (421–602 within the 376–610 superfamily envelope) to engage small GTPases and their effectors.

   This causes cycles of assembly that modulate adhesion and motility pathways—classically those governed by Rho-family and Rab-family GTPases—thereby tuning actin dynamics and vesicle routing that underpin kidney progenitor cell movements. I hypothesize preferential interactions with small GTPases (e.g., RALA/BET1-associated routes; RHOA/CDC42/RAC1 axes), along with their effectors and adaptors (GIT1–PIX, focal adhesion components), forming a cytosolic scaffold that relays signals into adhesion and migration programs essential for embryonic development.