Kelch repeat and BTB domain-containing protein 2 (KBTBD2)

Kelch repeat and BTB domain-containing protein 2 (KBTBD2) is a protein encoded by the KBTBD2 gene in humans. It functions as a substrate-specific adaptor in the BTB–Cullin3–Rbx1 (BCR) E3 ubiquitin ligase complex, which mediates Lys-48–linked polyubiquitination and subsequent proteasomal degradation of substrate proteins such as PIK3R1 (p85α), a major regulatory subunit of phosphatidylinositol 3-kinase (PI3K)[3][4]. By targeting p85α for degradation, KBTBD2 plays a crucial role in the regulation of insulin signaling and insulin sensitivity, particularly in adipocytes[4]. Mutations in KBTBD2 have been linked to SHORT syndrome, a rare disorder characterized by short stature, hyperextensibility, ocular depression, Rieger anomaly, and teething delay[4][2]. Structurally, KBTBD2 contains both BTB/POZ and kelch repeat domains, enabling extensive protein–protein interactions. KBTBD2 is not currently a target for approved drugs, and no validated pharmacological agents are known to interact with it[4]. The main therapeutic challenge in modulating this target is the risk of disrupting critical metabolic pathways and protein degradation mechanisms[2][4].

Other names

BKLHD1KIAA1489CGI-73DKFZP566C134BTB and kelch domain-containing protein 1kelch repeat and BTB (POZ) domain containing 2

Not applicable (since there are no drugs targeting KBTBD2 directly), but the mechanistic role in therapy would be via inhibition or modulation of ubiquitin-mediated degradation of substrates (e.g., targeting the degradation of PI3K regulatory subunit p85α)