Toll-like receptor 2 heterodimer (TLR2 heterodimer)

Toll-like receptor 2 (TLR2) heterodimers are essential pattern recognition receptors of the innate immune system that detect a broad spectrum of pathogen-associated molecular patterns (PAMPs) [1]. Unlike other Toll-like receptors that often function as homodimers, TLR2 must pair with either TLR1 or TLR6 to achieve functional specificity; the TLR2/1 complex recognizes triacylated lipopeptides primarily from Gram-negative bacteria, while the TLR2/6 complex recognizes diacylated lipopeptides from Gram-positive bacteria and mycoplasma [2][3]. These heterodimers are predominantly expressed on the plasma membrane of myeloid cells, such as monocytes, macrophages, and dendritic cells [4]. Upon activation, they signal through the MyD88-dependent pathway, leading to the activation of NF-κB and the subsequent release of pro-inflammatory cytokines and chemokines [5]. Due to their pivotal role in initiating inflammatory responses, TLR2 heterodimers are targeted in the development of therapies for sepsis, rheumatoid arthritis, and various cancers [6]. However, therapeutic modulation must be precisely calibrated, as excessive inhibition can lead to immunosuppression and increased vulnerability to pyogenic infections [7].

Other names

TLR2/1 complexTLR2/6 complexCD282/CD281CD282/CD286Toll-like receptor 2/1Toll-like receptor 2/6

TLR2 heterodimers function by binding specific acylated lipopeptides, which induces a conformational change that brings the intracellular Toll/Interleukin-1 receptor (TIR) domains together. This creates a scaffold for the recruitment of the adapter proteins Mal (TIRAP) and MyD88. The resulting complex, known as the myddosome, triggers a phosphorylation cascade involving IRAK family kinases and TRAF6, leading to the activation of the IKK complex and MAPK pathways. This results in the nuclear translocation of transcription factors like NF-κB and AP-1, driving the expression of genes involved in the inflammatory response.