Disease relevance of Syngr1

• A 29 kD soluble rat liver nucleoprotein (p29) has increased binding affinity for the hormone responsive element (RE) of the rat haptoglobin (Hp) gene during the acute-phase reaction [1].

High impact information on Syngr1

• The oncogene (Ra-v-ras) encodes a 29,000-dalton (p29) transforming protein [2].
• Synaptogyrin (p29) is a synaptic vesicle protein that is uniformly distributed in the nervous system (Baumert et al., 1990) [3].
• When the synaptogyrin cDNA is expressed in COS cells, the generated protein is indistinguishable from native synaptogyrin [3].
• To study intracellular sorting, synaptogyrin was expressed in CHO cells that revealed a punctate staining that was very similar to that of synaptophysin and endogenously expressed cellubrevin [3].
• Database searches revealed several cDNA sequences coding polypeptides with sequence identities ranging from 32 to 46%, suggesting that synaptogyrin is a member of a multigene family [3].

Biological context of Syngr1

• Deletion and mutational analysis with the use of GFP-tagged SNG-1 has defined a 38 amino acid sequence within the C terminus of SNG-1 and a single arginine in the cytoplasmic loop between transmembrane domain 2 and 3 that are required for SNG-1 localization [4].
• These domains may represent components of signals that target synaptogyrin for endocytosis from the plasma membrane and direct synaptogyrin to synaptic vesicles, respectively [4].
• On the basis of in vitro and in vivo phosphorylation/dephosphorylation experiments, we discuss the modulatory role of phosphate groups in view of the structure and function of p29 [1].

Anatomical context of Syngr1

• We report here that, in PC12 cells, cellugyrin is localized in synaptic-like microvesicles (SLMVs), along with synaptogyrin and synaptophysin [5].
• Synaptogyrin is an abundant membrane protein of synaptic vesicles containing four transmembrane regions and a C-terminal cytoplasmic tail that is tyrosine phosphorylated [6].
• Cellugyrin and synaptogyrin co-localize when transfected into COS cells but are differentially distributed in brain, the only tissue where both proteins are detectable [6].
• The distribution of p29 in various subcellular fractions from rat brain was very similar to that of synaptophysin and synaptobrevin [7].
• In chimeric studies, these regions were sufficient to relocalize cellugyrin, a nonneuronal form of synaptogyrin, from nonsynaptic regions such as the sensory dendrites and the cell body to synaptic vesicles [4].

Associations of Syngr1 with chemical compounds

• Thyroxine rapidly induced the inactivation of the deiodinase and initiated the binding of p29 to F-actin [8].
• Cyclic AMP stimulation leads to the translocation of p29 to the plasma membrane coincident with the appearance of deiodinating activity [9].
• Catalytic activities of p29 expressed in yeast were investigated. p29 had retinal reductase activity in the presence of NADPH [10].
• In this study, p29 cDNA was isolated by PCR with oligonucleotide probes designed from the N-terminal amino acid sequence and p29 was found to be a microsomal retinol dehydrogenase, a member of the short-chain alcohol dehydrogenase family which metabolize hydroxysteroids and prostaglandins [10].

Enzymatic interactions of Syngr1

• Cellugyrin, a novel ubiquitous form of synaptogyrin that is phosphorylated by pp60c-src [6].

Regulatory relationships of Syngr1

• Two monoclonal antibodies raised against p29 cross reacted with synaptophysin, indicating the presence of related epitopes [7].

Other interactions of Syngr1

• Cellugyrin and synaptogyrin facilitate targeting of synaptophysin to a ubiquitous synaptic vesicle-sized compartment in PC12 cells [5].
• Our previous studies in PC12 cells demonstrated that synaptogyrin or its nonneuronal paralog cellugyrin targets efficiently to synaptic-like microvesicles (SLMVs) and dramatically increases the synaptophysin content of SLMVs (Belfort, G. M., and Kandror, K. V. (2003) J. Biol. Chem. 278, 47971-47978) [11].
• We also found expression of the vesicle recycling proteins synaptogyrin and syntaxin-6 in the same region of the hair follicle [12].

Analytical, diagnostic and therapeutic context of Syngr1

• Using monospecific polyclonal antibodies, the distribution of p29 was studied in a variety of tissues by light and electron microscopy and immunoblot analysis [7].
• Gel filtration showed that p29 was part of a multimeric membrane-associated complex in both cAMP-stimulated and unstimulated astrocytes and that cAMP stimulation led to an increase of approximately 60 kDa in the mass of the holoenzyme [9].
• The results of two-dimensional gel electrophoresis, Southwestern and Western immunoblot analyses, showed that p29 and HMG1 are homologous protein species [1].
• 4. By sequencing and Western blotting analysis, the marked differences in the level of the p29/6.8 component were found to be due to carbonic anhydrase III [13].

References