C4BPB

Background

Complement C4 binding protein beta chain (C4BPB) is one of the two polypeptides of complement C4 binding protein (C4BP), a regulatory protein presenting in the fluid phase of normal plasma that plays an important role in the complement cascade. Usually, each C4BP protein complex contains a C4BPB chain. Human C4BPB is a 252-amino acid peptide encoded by the C4BPB gene, weighing about 28 kDa.

Similar to C4BPA, C4BPB also contains two cysteine residues and an amphipathic a-helix at the C-terminal, which are involved in disulfide-linkage polymerization. There are 3 complement control protein (CCP) repeat domains in human and rat C4BPB, while 2 CCPs in cattle C4BPB. In the human C4BPB, CCP1 domain is a critical binding site for the vitamin K-dependent Protein S, an anticoagulant plasma protein serving as a cofactor to activated protein C in the degradation of coagulation factors Va and VIIIa. Once C4BPB is bound to Protein S with high affinity, the C4BP-Protein S complex will inhibit the activation of the complement pathways on the apoptotic cells, on the other hand, prevents Protein S from acting as a cofactor in coagulation. It has been indicated that the CCP2 domain may not act as a binding site but localizes and stabilizes CCP1. The diseases associated with C4BPB mainly include Patellar Tendinitis and Cone-Rod Dystrophy 2.

Fig.1 C4BP structure^{.1, 3}

C4BPB Functional Service

Creative Biolabs offers an extensive range of products centered on C4BPB, comprising anti-C4BPB antibodies, ELISA kits, recombinant C4BPB proteins, vectors with C4BPB clones. These meticulously crafted regents are intended to enable the detection and analysis of interactions between complement components and C4BPB proteins. They are crucial for advancing research focused on developing therapeutic approaches for a range of diseases.

Fig.2 Serum concentrations of C4BPB in healthy individuals, tuberculosis patients, and those undergoing TB treatment.^{2, 3}

This research aimed to pinpoint novel biomarkers for pulmonary tuberculosis (TB). Researchers utilized two-dimensional liquid chromatography coupled with tandem mass spectrometry analysis to differentiate and identify aberrant proteins in the serum of TB patients. They discovered a number of proteins with abnormal expression, noting significant variations in some proteins when compared between TB patients and those with pneumonia or chronic obstructive pulmonary disease (COPD). By ELISA detecting, TB patients had elevated serum C4BPB levels compared to healthy controls, though lower than pneumonia or COPD patients. Post six-month treatment, serum amyloid A (SAA) and protein Z (PROZ) levels rose, while C4BPB levels decreased. Clinical assessments identified notable differences in coagulation and lipid indices, correlating PROZ with INR and C4BPB with fibrinogen in TB patients, suggesting C4BPB as a potential TB biomarker, offering crucial insights for differential diagnosis.

Creative Biolabs offers an extensive array of functional services centered on C4BPB, including thorough interaction analyses and various specialized assessments. These meticulously crafted services are designed to support researchers in progressing their scientific studies and clinical initiatives.

References

1. Breda, Leandro CD, et al. "Fine mapping of the interaction between C4b-binding protein and outer membrane proteins LigA and LigB of pathogenic Leptospira interrogans." PLoS neglected tropical diseases 9.10 (2015): e0004192.
2. Jiang, Ting-Ting, et al. "Serum amyloid A, protein Z, and C4b-binding protein β chain as new potential biomarkers for pulmonary tuberculosis." PloS one 12.3 (2017): e0173304.
3. Distributed under Open Access license CC BY 4.0, without modification.