NBPF7

Model summary

A human NBPF-family scaffold that uses tandem Olduvai repeats to assemble multivalent protein complexes controlling centrosome biology and downstream signaling. By clustering partners at the centrosome, it modulates the centrosome cycle and duplication, while enhancing IKK–NF-κB pathway throughput and transcriptional activity to favor survival and limit apoptosis. Its mechanism relies on high-avidity protein binding that organizes signaling and cytoskeletal hubs rather than catalysis.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The sequence is assigned to IPR055306 (NBPF family) spanning residues 6–415, establishing membership in the NBPF superfamily that characteristically lacks catalytic motifs and instead functions as modular scaffolds. Within this family envelope, two tandem Olduvai repeats are present: IPR010630 (Olduvai domain) from residues 190–279 followed immediately by another Olduvai domain from residues 280–391. The Olduvai repeat is an alpha-helical module that promotes multivalent protein–protein interactions and higher-order assembly. The ordered tandem Olduvai arrangement embedded in an NBPF scaffold creates a high-avidity binding platform rather than an enzyme active site. This architecture causally dictates a molecular role centered on multivalent complex assembly, consistent with GO:0005515 protein binding as the primary molecular function.

2. 02

   From this scaffolded binding capacity, I infer pathway-level roles by mapping how such assemblies influence signaling and cytoskeletal control.

   The NBPF–Olduvai tandem is well-suited to nucleate and stabilize signaling hubs that regulate cell fate and division. This explains participation in GO:0007165 signal transduction: by clustering kinases and adaptors, the scaffold tunes pathway throughput. Its capacity to potentiate transcriptional outputs downstream of IKK supports GO:0043123 positive regulation of I-kappaB kinase/NF-kappaB signaling and GO:0051092 positive regulation of NF-kappaB transcription factor activity; Olduvai-driven oligomerization increases local concentrations of IKK/NF-κB components, biasing them toward active states. The same assembly logic extends to cell-cycle governance: scaffolding at microtubule-organizing centers constrains duplication machinery, aligning with GO:0010824 regulation of centrosome duplication and GO:0046605 regulation of centrosome cycle. By stabilizing pro-survival signaling and restraining stress-induced death pathways, the scaffold contributes to GO:0043066 negative regulation of apoptotic process.

3. 03

   Cellular placement follows from the assembly’s purpose.

   The NBPF scaffold’s influence on centrosome duplication and cycle control points to a centrosomal niche, matching GO:0005813 centrosome. A centrosomal residence also rationalizes its impact on NF-κB signaling and survival: centrosomes act as signaling relays and hubs that coordinate cytoskeletal dynamics with transcriptional programs.

4. 04

   Mechanistically, I propose that the tandem Olduvai core forms oligomeric clusters that recruit centrosomal organizers and signaling adaptors.

   At the centrosome, this platform modulates duplication factors and couples them to cytoskeleton-responsive pathways. In parallel, transient assemblies with IKK and NF-κB regulators elevate pathway activity, tipping transcriptional programs toward survival and proliferation. Likely partners include centrosome and microtubule organizers (e.g., CEP and PCM components), duplication regulators (e.g., PLK and CEP proteins), and NF-κB pathway nodes (e.g., TRAF and IKK complexes). Together, these interactions explain how a non-enzymatic NBPF scaffold coordinates centrosome biology with NF-κB-driven signal transduction and apoptosis restraint.