title: Purification and partial characterization of analogous 26-kDa rat submandibular and parotid gland integral membrane phosphoproteins that may have a role in exocytosis.
abstract: Rat submandibular and parotid gland exocytosis is primarily controlled by beta-adrenergic receptor stimulation. Although its precise role in the regulation of salivary gland exocytosis is not fully understood, protein phosphorylation, mediated by the activation of cAMP-dependent protein kinase, may be directly involved. Previous studies suggest that analogous 26-kDa integral membrane phosphoproteins may play a direct role in regulating exocytosis. Studies were here undertaken to purify and partially characterize both phosphoproteins. After endogenous phosphorylation with 32P, subcellular fraction and solubilization of the microsomal fraction in n-octyl beta-glucopyranoside, the 26-kDa integral membrane phosphoproteins were purified by high performance liquid chromatography (HPLC), followed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and electroelution of the proteins. Amino acid analysis indicated a significant number of serine amino acids: N-terminal sequence data demonstrated a high level of homology; and trypsin digestion followed by reversed-phase HPLC indicated the possibility of multiple phosphorylation sites.
authors.affiliation: Department of Basic Sciences and Oral Research, School of Dentistry, University of Colorado, Denver 80262.
authors.forename: D O
authors.initials: DO
authors.lastname: Quissell
authors.forename: L M
authors.initials: LM
authors.lastname: Deisher
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005089:Exocytosis / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000302:isolation & purification* / Q000502:physiology*; D010306:Parotid Gland / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D010748:Phosphopeptides / Q000032:analysis; D010750:Phosphoproteins / Q000032:analysis / Q000302:isolation & purification* / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D012995:Solubility; D013363:Submandibular Gland / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism
chemical_list: D000596:Amino Acids; D008565:Membrane Proteins; D010748:Phosphopeptides; D010750:Phosphoproteins