Surfactant-associated protein G (SFTA2 (also SP-G))

Surfactant-associated protein G (SFTA2, also known as SP-G) is a recently identified, small, secreted protein composed of 78 amino acids with a molecular weight of about 8 kDa[2]. It is structurally and sequentially unrelated to the classical surfactant proteins A, B, C, or D. SFTA2 is encoded on human chromosome 6p21.33 and expressed in multiple tissues, including the lung (bronchiolar epithelium, possibly alveolar type II cells), ocular surface (conjunctiva, meibomian glands, lacrimal glands), kidney tubules, heart, testis (including spermatozoa), and possibly other secretory/epithelial tissues[2]. Structurally, SFTA2/SP-G is amphiphilic, with both hydrophilic and hydrophobic regions, and likely undergoes post-translational modifications such as phosphorylation, glycosylation, and palmitoylation. These features suggest a role similar to other surfactant proteins: regulating the physical properties and flow at biological interfaces by interacting with lipid layers. Unlike established surfactant proteins, it does not belong to any existing surfactant protein family or other typical protein family (e.g., collectins, receptors, enzymes). Experimental data demonstrate surface localization in relevant tissues, and molecular modeling supports its potential for lipid interaction, but its detailed physiological and pathological roles remain unclear. There is no current evidence supporting a role as a therapeutic target or biomarker, and no drugs are known to interact with this protein[2]. **Note:** SFTA2 (SP-G) is distinct from Surfactant protein A2 (SFTPA2 / SP-A2)[1]. They are different genes and proteins. The correct mapping for the user query is the novel "Surfactant-associated protein G (SFTA2)," not the well-known SFTPA2 gene/protein described in some sources[1].

Other names

Surfactant-associated protein 2SFTA2SFTPGSP-GUNQ541/PRO1098Surfactant-associated protein Gsurfactant associated protein GGSGL541UNQ541

None established for any therapeutic intervention; not a validated drug target