High impact information on Psp

• In situ hybridization and immunocytochemical localization demonstrated the presence of CSP1 transcripts and proteins in sublingual gland serous demilune cells, parotid and submandibular gland intercalated duct cells, and in the type III (proacinar) cells of the neonatal submandibular gland [1].
• Neonatal rat submandibular gland protein SMG-A and parotid secretory protein are alternatively regulated members of a salivary protein multigene family [2].
• Transcripts homologous to SMG-A and rat PSP, but more closely related to SMG-A, were identified in rat sublingual gland by Northern blot analysis [2].
• These findings indicate that rat SMG-A and PSP arise from alternatively regulated members of a multigene family [2].
• The leucine-rich protein shares extensive sequence homology with mouse PSP throughout its 5'-untranslated, protein coding and 3'-untranslated regions, prompting our suggestion that it should henceforth be referred to as rat PSP [2].

Biological context of Psp

• In addition to the previously observed sequence similarity, Psp and Smgb are highly homologous throughout exon 1 and at 365 of 600bp immediately upstream of the transcription start site [3].
• While Psp is expressed similarly in the mouse, the putative Smgb gene of the mouse seems not to be expressed, apparently due to the insertion, between exons 1 and 2, of a gene for a retroviral protein [4].
• Pancreatic Reg/pancreatic stone protein (PSP) gene expression does not correlate with beta-cell growth and regeneration in rats [5].
• Regulation of chloride transport in parotid secretory granules by membrane fluidity [6].
• These results indicate that in the parotid secretory granule there is a calcium uptake mechanism that is dependent on the hydrolysis of ATP and is suppressed by two inhibitors of granule ATPase [7].

Anatomical context of Psp

• Neonatal submandibular gland proteins B1 and B2, as well as apparent Mr 26000-28000 and Mr 18000-20000 forms in submandibular, sublingual and parotid glands, are derived from the gene encoding ZZ3 by differential N-glycosylation and by proteolytic cleavage [8].
• Psp and Smgb: a model for developmental and functional regulation in the rat major salivary glands [4].
• To test this hypothesis, parotid secretory protein (PSP), which is stored efficiently in parotid acinar cells, was expressed in the endocrine cell lines GH4C1 and PC12 [9].
• There was a rapid induction of the Reg/PSP gene in the remnant pancreas after a 90% pancreatectomy in rats during the period of marked growth of the exocrine and islet tissue [5].
• We show here that pancreatic plasma membranes fuse not only with pancreatic zymogen granules but also with parotid secretory granules [10].

Associations of Psp with chemical compounds

• Changes in patterns of feeding activity, parotid secretory enzymes and plasma corticosterone in developing rats [11].
• Pulse-chase experiments in the presence of the xyloside analog showed a significant reduction in the stimulated secretion and granule storage of the newly synthesized regulated secretory proteins amylase and parotid secretory protein [12].
• 45Ca2+ uptake in isolated rat parotid secretory granules was examined in the presence of oxalate [7].
• However, when 5-HT is infused along with a threshold concentration of acetylcholine (0.1 mmol/L), potentiation of parotid secretory response is seen with 5-HT (1 mumol/L, 260% increase; 10 mumol/L, 146% increase) [13].
• The presence of chondroitin sulfate in parotid secretory granules and saliva of the rat [14].

Other interactions of Psp

• Structure and chromosomal localization of the rat salivary Psp and Smgb genes [3].
• Subcellular fractionation of GH4C1 cells revealed that PSP co-fractionates with chromogranin A but not with secreted alkaline phosphatase [9].
• Involvement of aquaporin-5 water channel in osmoregulation in parotid secretory granules [15].
• Isoproterenol evoked decreases in alpha-amylase- and Rab3D-labelled parotid secretory granules, and pilocarpine stimulated decreases in secretory granules labelled for lingual lipase and Rab3D from von Ebner's glands, and amylase and Rab3D from pancreas [16].

Analytical, diagnostic and therapeutic context of Psp

• In order to understand these developmentally regulated changes in SMG salivary protein gene expression, we have initiated the molecular cloning and characterization of neonatal submandibular gland proteins from a 5-d-old rat submandibular gland cDNA library [17].
• Parotid secretory and vascular responses to electrical stimulation of the parasympathetic innervation were measured in anaesthetized rats [18].
• A longitudinal study of parotid secretory kinematics by cinemicrography and computer analysis [19].
• Rat parotid secretory granules were isolated by density gradient centrifugation and lysed in hypotonic buffers [20].

References