CD81 Protein, Human (HEK293, Fc)

The CD19 receptor is critical for B cell activation, driving the trafficking and assembly of CD19-CR2 and BCR complexes, thereby lowering the antigenic threshold for B cell clonal expansion. In T cells, CD19 contributes to CD3 localization and influences polarization. CD81 Protein, Human (HEK293, Fc) is the recombinant human-derived CD81 protein, expressed by HEK293 , with N-hFc labeled tag. The total length of CD81 Protein, Human (HEK293, Fc) is 89 a.a., with molecular weight of ~37 kDa.

CD19 receptor plays a crucial role in the trafficking and compartmentalization of activated B cells. It allows the assembly of CD19-CR2/CD21 and B cell receptor (BCR) complexes at signaling TERMs, leading to a lower threshold dose of antigen required to trigger B cell clonal expansion and antibody production. This receptor also facilitates the localization of CD247/CD3 zeta at antigen-induced synapses with B cells in T cells, providing costimulation and polarization toward T helper type 2 phenotype. Additionally, CD19 is present in MHC class II compartments and may play a role in antigen presentation. It can act as both a positive and negative regulator of cell-cell fusion processes. CD19 positively regulates sperm-egg fusion and may be involved in the acrosome reaction. In myoblasts, it associates with CD9 and PTGFRN to inhibit myotube fusion during muscle regeneration. In macrophages, CD19 associates with CD9 and beta-1 and beta-2 integrins to prevent macrophage fusion into multinucleated giant cells specialized in ingesting complement-opsonized large particles. It also prevents the fusion of mononuclear cell progenitors into osteoclasts responsible for bone resorption. CD19 may also regulate the compartmentalization of enzymatic activities. In T cells, it defines the subcellular localization of dNTPase SAMHD1 and permits its degradation by the proteasome, thereby controlling intracellular dNTP levels. CD19 is also involved in cell adhesion and motility, positively regulating integrin-mediated adhesion of macrophages, particularly in the inflammatory response in the lung. Additionally, CD19 acts as a receptor for hepatitis C virus (HCV) in hepatocytes, in association with CLDN1 and the CLDN1-CD81 receptor complex, essential for HCV entry into host cells.

Human

HEK293

N-hFc

P60033 (F113-K201)

975  [NCBI]

FVNKDQIAKDVKQFYDQALQQAVVDDDANNAKAVVKTFHETLDCCGSSTLTALTTSVLKNNLCPSGSNIISNLFKEDCHQKIDDLFSGK

Approximately 37 kDa

Greater than 95% as determined by reducing SDS-PAGE.

Lyophilized powder.

Lyophilized from a 0.2 μm filtered solution of PBS, pH 7.4.

<1 EU/μg, determined by LAL method.

It is not recommended to reconstitute to a concentration less than 100 μg/mL in ddH₂O. For long term storage it is recommended to add a carrier protein (0.1% BSA, 5% HSA, 10% FBS or 5% Trehalose).

Stored at -20°C for 2 years. After reconstitution, it is stable at 4°C for 1 week or -20°C for longer (with carrier protein). It is recommended to freeze aliquots at -20°C or -80°C for extended storage.

Room temperature in continental US; may vary elsewhere.