Retinol binding protein 4 Human E. coli

Introduction to the Molecule

Retinol binding protein (RBP) 4 is the only specific transport protein for vitamin A in the circulation whose function is to deliver vitamin to target tissues (1). In obesity and type 2 diabetes, expression of Glut4 is significantly impaired in adipocytes. Glucose transport via Glut4 is the rate-limiting step for glucose use by muscle and adipose tissue (2). Yang et al. noted that adipocyte-specific deletion of Gluts led to notable elevation of RBP4 causing systemic insulin resistance, and that reduction of RBP4 improved insulin resistance (3). This identified a novel role of RBP4 in regulating insulin action and RBP4 is recorded as an adipocyte-derived hormone. Thus, measurement of serum or plasma RBP4 is a useful means for understanding of metabolic disorders.

Research topic

Diabetology - Autoimmunity, Energy metabolism and body weight regulation

Description

Total 204 AA. MW: 23 kDa (calculated). N-terminal His-tag, 21 extra AA (highlighted). The AA sequence is identical to UniProtKB/Swiss-Prot entry Q5VY30 (AA16–199).

Amino Acid Sequence

Source

E. coli

Purity

95%, as determined by SDS-PAGE.

SDS-PAGE gel

12% SDS-PAGE separation of Human RBP4 1. M.W. marker – 14, 21, 31, 45, 66, 97 kDa 2. reduced and heated sample, 5μg / lane 3. non-reduced and non-heated sample, 5μg / lane

Biological Activity

Determined by its ability to bind all trans retinol acids. The binding of RBP4 to all trans retinol acids results in quenching of Trp fluroscence. 0.5 M retinol acids/per M RBP4.

Endotoxin

<0.5 EU/ug protein.

Formulation

Filtered (0.4 μm) and lyophilized from 0.5 mg/ml in PBS buffer, pH 7.5

Reconstitution

Add deionized water to prepare a working stock solution of approximately 0.5 mg/mL and let the lyophilized pellet dissolve completely. Product is not sterile! Please filter the product by an appropriate sterile filter before using it in the cell culture.

Storage, Stability/Shelf Life

Store lyophilized protein at –20°C. Lyophilized protein remains stable until the expiry date when stored at –20°C. Aliquot reconstituted protein to avoid repeated freezing/thawing cycles and store at –80°C for long term storage. Reconstituted protein can be stored at 4°C for a limited period of time; it does not show any change after one week at 4°C.

Quality Control Test

BCA to determine quantity of the protein.

SDS PAGE to determine purity of the protein.

Applications

Binding assay, ELISA, Western blotting

Note

This product is intended for research use only.

References

• Kahn BB, Shepherd PR. Glucose transporters and insulin action--implications for insulin resistance and diabetes mellitus. N Engl J Med. 1999 Jul 22;341 (4):248-57
• Quadro L, Blaner WS, Salchow DJ, Vogel S, Piantedosi R, Gouras P, Freeman S, Cosma MP, Colantuoni V, Gottesman ME. Impaired retinal function and vitamin A availability in mice lacking retinol-binding protein. EMBO J. 1999 Sep 1;18 (17):4633-44
• Yang Q, Graham TE, Mody N, Preitner F, Peroni OD, Zabolotny JM, Kotani K, Quadro L, Kahn BB. Serum retinol binding protein 4 contributes to insulin resistance in obesity and type 2 diabetes. Nature. 2005 Jul 21;436 (7049):356-62

By research topic:

• Diabetology - Autoimmunity
• Energy metabolism and body weight regulation

By molecule:

• Retinol Binding Protein 4