[1][2][3][4][5][6]11477057757ENSG00000161031ENSMUSG00000079563Q96PD5Q8VCS0NM_052890NM_001363546NM_001271476NM_001271477NM_001271478NM_001271479NM_021319NP_443122NP_001350475NP_001258405NP_001258406NP_001258407NP_001258408NP_067294The N-acetylmuramoyl-L-alanine amidase enzymatic activity was first observed in human and mouse serum in 1981 by Branko Ladešić and coworkers.

In 2000, Dan Hultmark and coworkers discovered a family of 12 Peptidoglycan Recognition Protein (PGRP) genes in Drosophila melanogaster and by homology searches of available human and mouse sequences predicted the presence of long forms of human and mouse PGRPs, which they named PGRP-L by analogy to long forms of insect PGRPs.

[17] In 2001, Roman Dziarski and coworkers discovered and cloned three human PGRPs, named PGRP-L, PGRP-Iα, and PGRP-Iβ (for long and intermediate size transcripts),[1] and established that human genome codes for a family of 4 PGRPs: PGRP-S (short PGRP)[18] and PGRP-L, PGRP-Iα, and PGRP-Iβ.

Recombinant and native human PGLYRP2 proteins were then further shown to be identical with the previously identified and purified serum NAMLAA.

[23] PGLYRP2 is also expressed to a much lower level in the colon, lymph nodes, spleen, thymus, heart, and polymorphonuclear leukocyte granules.

[27][30] Constitutive and induced expression of PGLYRP2 is controlled by different transcription factors whose binding sequences are located in different regions of the PGLYRP2 promoter.

[1][3][34] PGLYRP2 also has a long N-terminal segment that comprises two thirds of the PGLYRP2 sequence, has two hydrophobic regions, is not found in other mammalian PGLYRP1, PGLYRP3, and PGLYRP4 and in invertebrate PGRPs, and is unique with no identifiable functional motifs or domains.

[1][3][34] PGLYRP2 has two pairs of cysteines in the PGRP domain that are conserved in all human PGRPs and are predicted to form two disulfide bonds.

[15] PGLYRP2, similar to all other amidase-active PGRPs (invertebrate and vertebrate), has a conserved Zn2+-binding site in the peptidoglycan-binding cleft, which is also present in bacteriophage type 2 amidases and consists of two histidines, one tyrosine, and one cysteine (His411, Tyr447, His522, Cys530 in human PGLYRP2).

PGLYRP2 is an enzyme (EC 3.5.1.28), N-acetylmuramoyl-L-alanine amidase, that binds and hydrolyzes bacterial cell wall peptidoglycan.

[1][3][4][11][12][13][14][15][16][35] Peptidoglycan is the main component of bacterial cell wall and is a polymer of β(1-4)-linked N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) with MurNAc-attached short peptides, typically composed of alternating L and D amino acids, that cross-link the adjacent polysaccharide chains.

[39][40] PGLYRP2 directly and indirectly affects inflammation and plays a role in maintaining anti- and pro-inflammatory homeostasis in the intestine, skin, joints, and brain.

[47][48][49] Increased serum PGLYRP2 levels are present in patients with systemic lupus erythematosus and correlate with disease activity index, renal damage, and abnormal lipid profile.