aTyr 1940 is a recombinant 506 amino acid version of human histidyl-tRNA synthetase (cytoplasmic isoform 1) (HARS
]. HARS belongs to a novel group of naturally occurring proteins termed 'physiocrines' which are extracellular signaling regions of tRNA synthetases reported to modulate immune system pathways. Physiocrines are of interest to the pharmaceutical industry as molecular targets for immunomodulatory therapies (see patents WO2013123432 A2 and US20150093799 A1 for further details [1-2
]). See also resokine
, a shorter variant of aTyr 1940.