Submaxillary gland androgen-regulated protein 3B (SMR3B)

Submaxillary gland androgen-regulated protein 3B (SMR3B) is a human secreted salivary protein encoded by the SMR3B gene, primarily expressed in the submaxillary (submandibular) glands and regulated by androgens[1][2][7][13]. It belongs to the proline-rich protein family, which is abundant in saliva and performs several physiological functions[3][6]. SMR3B functions as an endopeptidase inhibitor and is involved in modulating pain perception, regulating cellular response to microbial components such as lipopolysaccharides, and binding calcium ions[12][13]. In saliva, proline-rich proteins including SMR3B are important for maintaining ionic calcium balance, inhibiting the formation of hydroxyapatite (preventing calculus and unwanted mineral deposition on teeth), and possibly acting as lubricants and tannin precipitants, contributing to oral health and defense against dietary compounds and pathogens[3][9]. There is limited direct evidence for SMR3B as a classical therapeutic target (i.e., receptor, enzyme, transporter, etc.), and no established drug interactions or biomarker roles as of current knowledge[2][12][13]. Clinical associations are sparse but include links to sialolithiasis (salivary gland stones) and orange allergy, likely due to altered secretory function or immune responses[2].

Other names

Peptide P-APeptide D1AP-BPRL3PROL3PBIIProline-rich peptide P-BProline-rich protein 3SMR1Bsalivary proline-rich proteinsubmaxillary gland androgen regulated protein 3 homolog Bproline rich 3