Recombinant Human SPOP

Background: Speckle-type POZ protein (SPOP) is a substrate adaptor for the CUL3-RBX1 E3 ubiquitin ligase complex, where it mediates selective recognition and ubiquitylation of target proteins. SPOP contains an N-terminal MATH domain responsible for substrate binding and a BTB/POZ domain that facilitates dimerization and interaction with CUL3, enabling efficient assembly of active ligase complexes. SPOP plays a central role in maintaining cellular proteostasis through the regulation of substrates involved in transcription, signal transduction, and protein turnover. Dysregulation or mutation of SPOP has been implicated in multiple cancers, highlighting its importance in disease biology and targeted protein degradation research. This recombinant SPOP protein contains N- and C-terminal truncations designed to improve solubility and stability while preserving the functional domains required for substrate recognition and CUL3-based ligase complex assembly. The protein is suitable for in vitro ubiquitylation assays, substrate identification, and mechanistic studies of CUL3-based ligase activity.