Identity of human extra parotid glycoprotein (EP-GP) with secretory actin binding protein (SABP) and its biological properties.
In this paper the identity of the salivary protein EP-GP (extra-parotid glycoprotein) is reported, also apparent in other human secretions. Immunochemical and biochemical analysis demonstrated that EP-GP is similar to the secretory actin-binding protein (SABP), also known as gross cystic disease fluid protein-15 (GCDFP-15) and prolactin-inducible protein (PIP). The molecular mass and charge microheterogeneity of EP-GP, also observed for SABP, was shown to be predominantly caused by the carbohydrate moiety. In addition, evidence was given that EP-GP is not related to the lipocalin Von Ebner's gland protein (human; VEGh). The biological significance of EP-GP and its homologues is not clear. EP-GP bound to actin and fibrinogen as described for SABP and GCDFP-15. However, the affinity for these proteins does not appear to have any direct physiological role in the mucosal secretions. On the other hand, EP-GP binds to several bacteria. By electron microscopy the ultrastructural localization is demonstrated of EP-GP to the cell wall of both Streptococcus salivarius HB and its cell appendage-lacking mutant Streptococcus salivarius HB-C12. Concerning this finding we hypothesize on the possible functional aspects of this enigmatic protein EP-GP.
Department of Oral Biochemistry, Vrije Universiteit, Amsterdam, The Netherlands.
L C
LC
Schenkels
J
J
Schaller
E
E
Walgreen-Weterings
I L
IL
Schadee-Eestermans
E C
EC
Veerman
A V
AV
Nieuw Amerongen
D000595:Amino Acid Sequence; D001053:Apolipoproteins; D053399:Apolipoproteins D; D002241:Carbohydrates / Q000032:analysis; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D006023:Glycoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D008297:Male; D026901:Membrane Transport Proteins; D008840:Microfilament Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009928:Organ Specificity; D012471:Salivary Proteins and Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D012661:Semen; D012669:Seminal Vesicles; D017386:Sequence Homology, Amino Acid; D013291:Streptococcus / Q000378:metabolism* / Q000648:ultrastructure; D013363:Submandibular Gland
C024328:APOD protein, human; D001053:Apolipoproteins; D053399:Apolipoproteins D; D002241:Carbohydrates; D002352:Carrier Proteins; D006023:Glycoproteins; D026901:Membrane Transport Proteins; D008840:Microfilament Proteins; C488892:PIP protein, human; D012471:Salivary Proteins and Peptides; C084741:extra parotid glycoprotein, human