Background
Transferrin, also known as transferrin (TRF, Tf), is responsible for carrying iron absorbed by the digestive tract and iron released by red blood cell degradation. It enters the bone marrow in the form of trivalent iron complex (Tf-Fe3+) for the production of mature red blood cells. Transferrin is mainly present in plasma. The transferrin in plasma supplies iron to most tissues of the body, while in areas that it cannot reach, the transferrin synthesized by these tissues themselves produces iron transfer in the local area.
Figure 1. Structure of transferrin
Human transferrin is mainly synthesized in the liver. It is a single-chain glycoprotein composed of two lobes located at the homologous N-terminus and C-terminus. Human transferrin contains 678 amino acid residues, an isoelectric point of 5.9, and a molecular weight of 76kD. Each molecule of transferrin can carry 2 trivalent iron ions (Fe3+). The interaction between transferrin and Fe3+ depends on pH. At pH 7.4, transferrin and Fe3+ bind efficiently, and the two separate at acidic pH.
Existence
Holo-Transferrin 、Partially saturated transferrin、Apo-Transferrin
Functional Mechanisms
Transferrin (Tf) binds iron by interacting with its receptor, Transferrin Receptor 1 (TfR1). TfR1 is a glycoprotein expressed on the cell surface, composed of two homodimeric subunits connected by disulfide bonds. On the cell surface, Tf interacts with Fe3+ to form holo-Tf, and binds to the TfR1 receptor, entering the endosome under endocytosis. In the acidic endosome environment, Fe3+ separates from Tf, and STEAP3 reduces Fe3+ to Fe2+, which is transported to the cytoplasm by divalent metal ion transporter 1 (DMT1). Then, Tf that releases Fe3+ forms a Tf/TfR1 complex with TfR1 and migrates back to the cell surface through exocytosis. On the cell surface, transferrin (Tf) separates from the receptor TfR1 to become apo-Tf, and then rebinds with Fe3+ to participate in the iron cycle. After the whole process is completed, Tf and TfR1 are recycled and enter the next cycle of cellular iron uptake.
Figure 2. Mechanism diagram of transferrin cycle[1]
The main function of transferrin
- Avoid the generation of free radicals and protect cell growth.
- Antibacterial, sterilizing, detoxifying
- Maintain cell proliferation and growth
- Promotes extracellular iron storage and transport
Sources of transferrin
|
Source |
Safety |
Batch Differences |
|
|
Naturally extracted transferrin |
Extract from human and bovine plasma |
Poor safety, the final product may contain pathogens |
Transferrin is extracted from different batches of human serum or bovine serum, and its performance varies greatly |
|
Recombinant transferrin |
Expressed from prokaryotic and eukaryotic cells |
Good safety, the final product does not contain pathogens |
Each batch is expressed using the same cell line, with stable performance |
Product Features
Good safety: The product has passed multiple layers of quality inspection and testing, avoiding contamination by pathogens;
Low toxicity: The cytotoxicity is very low and has no impact on subsequent experiments;
Stable performance: Each batch is expressed from the same cell line, with minimal performance differences and high protein purity
Easy to operate: simply add the product to the base;
Widely applicable: can be used for the cultivation of different types of cells.
FAQ
Q1: Should extracted transferrin or recombinant transferrin be added to serum-free culture medium?
A: Extracted transferrin has defects such as poor safety and large batch-to-batch differences. In particular, when extracted transferrin is added to serum-free culture medium for cell culture, it may bring human or animal pathogens (such as mad cow disease virus, Creutzfeldt-Jakob virus and other unknown pathogens) into cells and contaminate cells. Recombinant transferrin completely avoids the possibility of pathogen contamination, so recombinant transferrin should be added to serum-free culture medium.
Q2: Should iron-saturated (Holo) transferrin or apo (Apo) transferrin be added to culture medium?
A: When the culture medium does not contain iron or the iron content is low, choose to add iron-saturated (Holo) transferrin; when the culture medium is rich in iron, choose apo transferrin.
Q3: Which one is better, iron-saturated (Holo) transferrin or apo (Apo) transferrin?
A: It is impossible to infer the effect of the two theoretically, and experimental testing is required.
Q4: What is the concentration of transferrin in serum-free culture medium?
Answer: The concentration of transferrin is related to the cell type. The specific concentration is related to the cell state, cell concentration, and experimental purpose. General primary cells: 5-100 mg/L; Chinese hamster ovary cells: 10-50 mg/L; hybridoma and Vero cells: 5-20 mg/L
Ordering information
|
Product Name |
Product Number |
Specification |
|
Bovine Transferrin, APO） |
100 mg |
|
|
Bovine Transferrin (HOLO) |
40103ES60/80 |
100 mg/1g |
|
Human Transferrin（Derived from human plasma） |
40133ES60/76/80 |
100 mg/500 mg/1g |
|
Recombinant Human Holo-Transferrin |
92288ES60/76/80 |
100 mg/500 mg/1g |
|
Recombinant Human Apo-Transferrin Protein |
92289ES60/76/80 |
100 mg/5 |