CD4

In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 (after the OKT4 monoclonal antibody that reacted with it) before being named CD4 in 1984. In humans, the CD4 protein is encoded by the CD4 gene. CD4+ T helper cells are white blood cells that are an essential part of the human immune system. They are often referred to as CD4 cells, T-helper cells or T4 cells. They are called helper cells because one of their main roles is to send signals to other types of immune cells, including CD8 killer cells, which then destroy the infectious particle. If CD4 cells become depleted, for example in untreated HIV infection, or following immune suppression prior to a transplant, the body is left vulnerable to a wide range of infections that it would otherwise have been able to fight. Like many cell surface receptors/markers, CD4 is a member of the immunoglobulin superfamily. It has four immunoglobulin domains (D1 to D4) that are exposed on the extracellular surface of the cell: D1 and D3 resemble immunoglobulin variable (IgV) domains. D2 and D4 resemble immunoglobulin constant (IgC) domains. The immunoglobulin variable (IgV) domain of D1 adopts an immunoglobulin-like β-sandwich fold with seven β-strands in 2 β-sheets, in a Greek key topology. CD4 interacts with the β2-domain of MHC class II molecules through its D1 domain. T cells displaying CD4 molecules (and not CD8) on their surface, therefore, are specific for antigens presented by MHC II and not by MHC class I (they are MHC class II-restricted). MHC class I contains Beta-2 microglobulin. The short cytoplasmic/intracellular tail (C) of CD4 contains a special sequence of amino acids that allow it to recruit and interact with the tyrosine kinase Lck.

Machine learning predictions of MHC-II specificities reveal alternative binding mode of class II epitopes

Florence Pojer, George Coukos, Kelvin Ka Ching Lau, Amédé Noredine Larabi, Julien Racle, David Gfeller, Marta Andreia Da Silva Perez, Alexandre Harari

CD4+T cells orchestrate the adaptive immune response against pathogens and cancer by recognizing epitopes presented on class II major histocompatibility complex (MHC-II) molecules. The high polymorphism of MHC-II genes represents an important hurdle toward ...

CELL PRESS2023

Mechanism of Reduction of Aqueous U(V)-dpaea and Solid-Phase 2 U(VI)-dpaea Complexes: The Role of Multiheme c‑Type Cytochromes

Marinella Mazzanti, Rizlan Bernier-Latmani, Karin Lederballe Meibom, Margaux Camille Andréa Molinas, Radmila Faizova

The biological reduction of soluble U(VI) complexes to form immobile U(IV) species has been proposed to remediate contaminated sites. It is well established that multiheme c-type cytochromes (MHCs) are key mediators of electron transfer to aqueous phase U( ...

2023

Label-free plasmonic microarray for multiplexed analysis of cells and tumor organoids

Machine learning predictions of MHC-II specificities reveal alternative binding mode of class II epitopes

Mechanism of Reduction of Aqueous U(V)-dpaea and Solid-Phase 2 U(VI)-dpaea Complexes: The Role of Multiheme c‑Type Cytochromes

Label-free plasmonic microarray for multiplexed analysis of cells and tumor organoids

Mechanism of Reduction of Aqueous U(V)-dpaea and Solid-Phase 2 U(VI)-dpaea Complexes: The Role of Multiheme c‑Type Cytochromes

Machine learning predictions of MHC-II specificities reveal alternative binding mode of class II epitopes