Substrate recognition component of a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (PubMed:10097128, PubMed:16371461, PubMed:18782782, PubMed:9859996, PubMed:9990853, PubMed:21911472, PubMed:29593216). Recognizes and binds to phosphorylated target proteins (PubMed:10097128, PubMed:16371461, PubMed:18782782, PubMed:9859996, PubMed:9990853, PubMed:21911472). SCF(BTRC) mediates the ubiquitination of phosphorylated NFKB, ATF4, CDC25A, DLG1, FBXO5, PER1, SMAD3, SMAD4, SNAI1 and probably NFKB2. SCF(BTRC) mediates the ubiquitination of CTNNB1 and participates in Wnt signaling (By similarity). SCF(BTRC) mediates the ubiquitination of NFKBIA, NFKBIB and NFKBIE; the degradation frees the associated NFKB1 to translocate into the nucleus and to activate transcription (PubMed:9859996, PubMed:10097128). Ubiquitination of NFKBIA occurs at 'Lys-21' and 'Lys-22' (PubMed:9859996, PubMed:10097128). SCF(BTRC) mediates the ubiquitination of CEP68; this is required for centriole separation during mitosis (By similarity). SCF(BTRC) mediates the ubiquitination and subsequent degradation of nuclear NFE2L1 (PubMed:21911472). Has an essential role in the control of the clock-dependent transcription via degradation of phosphorylated PER1 and PER2 (PubMed:18782782). May be involved in ubiquitination and subsequent proteasomal degradation through a DBB1-CUL4 E3 ubiquitin-protein ligase (By similarity). Required for activation of NFKB-mediated transcription by IL1B, MAP3K14, MAP3K1, IKBKB and TNF (By similarity). Required for proteolytic processing of GLI3 (PubMed:16371461). Mediates ubiquitination of REST, thereby leading to its proteasomal degradation (By similarity). SCF(BTRC) mediates the ubiquitination and subsequent proteasomal degradation of KLF4; thereby negatively regulating cell pluripotency maintenance and embryogenesis (PubMed:29593216). Protein modification; protein ubiquitination. Homodimer. Self-associates. Component of the SCF(BTRC) complex, composed of SKP1, CUL1 and BTRC. Direct interaction with SKP1 with SKP1 occurs via the F-box domain. Interacts with phosphorylated ubiquitination substrates SMAD3 and SMAD4. Interacts with phosphorylated ubiquitination substrates CTNNB1, NFKBIA, NFKBIB, NFKBIE, NFKB1/nuclear factor NF-kappa-B p105 subunit, ATF4, CDC25A, DLG1, FBXO5 and SNAI1; the interaction requires the phosphorylation of the 2 serine residues in the substrate destruction motif D-S-G-X(2,3,4)-S. Binds UBQLN1. Interacts with CDC34 and UBE2R2. Interacts with FBXW11. Interacts with CUL4A and DDB1. Part of a SCF(BTRC)-like complex lacking CUL1, which is associated with phosphorylated NKBIA and RELA; RELA interacts directly with NFKBIA. Interacts with the phosphorylated form of GLI3. Interacts with CLU. Interacts with PER1 (phosphorylated), PER2 (phosphorylated) and PER3. Interacts with phosphorylated ubiquitination substrate CEP68 (By similarity). Interacts with ZC3H12A; this interaction occurs when ZC3H12A is phosphorylated in a IKBKB/IKKB-dependent manner (PubMed:22037600). Interacts with HSF1; this interaction occurs during mitosis and induces HSF1 ubiquitin-dependent degradation, a process inhibited by CDC20 (By similarity). Interacts with NFE2L1 (PubMed:21911472). Interacts with INAVA (By similarity). Interacts with IL10RA; this interaction leads to IL10RA ubiquitination and subsequent degradation (By similarity). Interacts with REST (By similarity). Interacts with KLF4; this interaction leads to KLF4 ubiquitination and subsequent degradation (PubMed:29593216). Expressed in heart, brain, liver, skeletal muscle and, most strongly, in testis. The N-terminal D domain mediates homodimerization. Mutants have normal circadian behavior with normal PER2 expression in the suprachiasmatic nucleus. PubMed:10531037 wrongly lists the species as human. Extended N-terminus.