LRG1 (leucine-rich 伪2-glycoprotein), also known as LRG, is a 347 amino acid secreted protein that contains 8 LRR (leucine-rich) repeats and one LRRCT domain. The leucine-rich repeat (LRR) family of proteins, including LRG1, have been shown to be involved in protein-protein interaction, signal transduction, cell adhesion and development. Found mainly in plasma, LRG1 is expressed during granulocyte differentiation. The gene that encodes LRG1 consists of nearly 3,000 bases and maps to human chromosome 19p13.3. Chromosome 19 consists of over 63 million bases, houses approximately 1,400 genes and is recognized for having the greatest gene density of the human chromosomes. It is the genetic home for a number of immunoglobulin (Ig) superfamily members, including the killer cell and leukocyte Ig-like receptors, a number of ICAMs, the CEACAM and PSG families and Fc receptors (FcRs).