Table 1.
General information on AMPs in female reproductive tract (FRT).
| AMPs | Encoded Gene | General Structures | Expression Sites in Normal FRT | Refs |
|---|---|---|---|---|
| HBD2 (Beta-defensin 2) |
DEFB4 | 64 amino acids. Amphiphilic monomer. Triple-stranded, antiparallel beta sheet with strands 2 and 3 in a beta hairpin conformation. | All sites of FRT except the fallopian tubes. | [42] |
| HBD3 (Beta-defensin 3) |
DEFB3 | 45 amino acids. Amphiphilic symmetrical dimer formed through strand beta2 of the beta-sheet. | Endometrium, vagina and cervix. | [43] |
| HNP2 (Human neutrophil peptide 2) |
DEFA1 | 29 amino acids. An N-terminal truncated structure containing three pairs of intramolecular disulfide bond. | Cervix. | [44] |
| HD5 (Human α-defensin 5) |
DEFA5 | 94 amino acids. A cationic peptide which is linked by three intra-molecular disulfide bridges, and contains six intra-molecular cysteine residues. | Endometrial, cervical and vaginal. | [45,46] |
| hCAP-18/LL-37 (Cathelicidin) |
CAMP | 37 amino acids. Amphiphilic, monomeric, α-helical peptide. | Endometrium, vagina, cervix and ovary. | [47] |
| SLPI (secretory leukocyte protease inhibitor) |
SLPI | 132 amino acids. A single-chain protein with eight intramolecular disulfide bonds. | Fallopian tube, endometrium, cervix and cervicovaginal fluid. | [48] |
| Elafin | PI3 | 117 amino acids. A structure maintained by four conserved disulfide bridges characteristic of WAP (whey acidic protein) family. | All epithelial cells lining the FRT. | [49] |
| HE4 (Human Epididymis Protein 4) |
WFDC2 | 124 amino acids. A glycoprotein containing a WAP domain (4-disulfide core domain 2). | Fallopian tubes, uterus, cervix and bartholin glands. | [50] |
| Lysozyme | LYZ | 129 amino acids. A single polypeptide. | Cervix and vagina. | [33] |
| Calprotectin | S100A8 S100A9 |
A complex of proteins S100A8 (93 amino acids) and S100A9 (113 amino acids). | Cervix and cervicovaginal fluid. | [36] |
| Psoriasin (S100A7) |
S100A7 | 101 amino acids. A member of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. | Vulva, vagina and ectocervix. | [51] |
| SP-A (surfactant protein A) |
SFTPA | 248 amino acids. The mature form of SP-A includes: an N-terminal segment, a collagen region, a neck region and a carbohydrate recognition domain(CRD). | Vagina. | [52] |
| SP-D | SFTPD | 375 amino acids. Each SP-D subunit is composed of an N-terminal domain, a collagenous region, a nucleating neck region, and a C-terminal lectin domain. | Endometrium, cervix, vagina and fallopian tubes. | [53] |
| Lactoferrin | LTF | 710 amino acids. A simple polypeptide chain folded into two symmetrical lobes (N and C lobes), which are highly homologous with one another. | Ovary, fallopian tubes and endometrium. | [54] |