About TLR4
The protein encoded by this gene is a member of the Toll-like receptor (TLR) family which plays a fundamental role in pathogen recognition and activation of innate immunity. TLRs are highly conserved from Drosophila to humans and share structural and functional similarities. They recognize pathogen-associated molecular patterns that are expressed on infectious agents, and mediate the production of cytokines necessary for the development of effective immunity. The various TLRs exhibit different patterns of expression. In silico studies have found a particularly strong binding of surface TLR4 with the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus disease-2019 (COVID-19). This receptor has also been implicated in signal transduction events induced by lipopolysaccharide (LPS) found in most gram-negative bacteria. Mutations in this gene have been associated with differences in LPS responsiveness, and with susceptibility to age-related macular degeneration. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Aug 2020]

About PE
Phycoerythrin (PE, R-PE) is a red-emitting fluorescent protein-chromophore complex that can be excited the 488-nm blue, 532-nm green, or 561-nm yellow-green laser with increasing efficiency and captured with a 586/14 nm bandpass filter. PE has an excitation peak at 565 nm and an emission peak at 578 nm. PE is 240kD in size and has an extinction coefficient of ~2x10^6 which makes it one of the brightest fluorophores available and a potent donor upon which to build tandem fluorophores with longer Stoke's Shifts.