Inzitari Rosanna, Cabras Tiziana, Rossetti Diana Valeria, Fanali Chiara, Vitali Alberto, Pellegrini Mariagiuseppina, Paludetti Gaetano, Manni Armando, Giardina Bruno, Messana Irene, Castagnola Massimo
Istituto di Biochimica e Biochimica Clinica, Università Cattolica, Rome, Italy.
Proteomics. 2006 Dec;6(23):6370-9. doi: 10.1002/pmic.200600395.
Statherin is a multifunctional polypeptide specific of human saliva involved in oral calcium homeostasis, phosphate buffering and formation of protein networks. Salivary P-B peptide is usually included into the basic proline-rich protein family but it shows some similarities with statherin and its specific biological role is still undefined. In this study, various fragments and derivatives of statherin and P-B peptide were consistently detected by RP-HPLC ESI-IT MS in 23 samples of human saliva. They were: statherin mono- and non-phosphorylated, statherin Des-Phe(43) (statherin SV1), statherin Des-Thr(42),Phe(43), statherin Des-Asp(1), statherin Des(6-15) (statherin SV2), statherin Des(1-9), statherin Des(1-10), statherin Des(1-13) and P-B Des(1-5). Statherin SV3 (statherin Des(6-15), Phe(43)) was detected only in one sample. Identity of the fragments was confirmed either by MS/MS experiments or by enzymatic digestion or by Edman sequencing. Detection of the fragments suggests that statherin and P-B peptide are submitted to post-translational proteolytic cleavages that are common to other classes of salivary proteins.
富含组氨酸的磷蛋白是一种人类唾液特有的多功能多肽，参与口腔钙稳态、磷酸盐缓冲和蛋白质网络的形成。唾液P - B肽通常被归入富含脯氨酸的基础蛋白家族，但它与富含组氨酸的磷蛋白有一些相似之处，其特定生物学作用仍不明确。在本研究中，通过反相高效液相色谱 - 电喷雾离子阱质谱法在23份人类唾液样本中持续检测到了富含组氨酸的磷蛋白和P - B肽的各种片段及衍生物。它们分别是：单磷酸化和非磷酸化的富含组氨酸的磷蛋白、去苯丙氨酸（43）富含组氨酸的磷蛋白（富含组氨酸的磷蛋白SV1）、去苏氨酸（42） - 苯丙氨酸（43）富含组氨酸的磷蛋白、去天冬氨酸（1）富含组氨酸的磷蛋白、去（6 - 15）富含组氨酸的磷蛋白（富含组氨酸的磷蛋白SV2）、去（1 - 9）富含组氨酸的磷蛋白、去（1 - 10）富含组氨酸的磷蛋白、去（1 - 13）富含组氨酸的磷蛋白以及去（1 - 5）P - B肽。仅在一个样本中检测到了富含组氨酸的磷蛋白SV3（去（6 - 15） - 苯丙氨酸（43）富含组氨酸的磷蛋白）。通过串联质谱实验、酶切或埃德曼测序确认了这些片段的身份。这些片段的检测表明，富含组氨酸的磷蛋白和P - B肽会经历翻译后蛋白水解切割，这在其他类别的唾液蛋白中很常见。
