Biomaterial Database

Synaptotagmin IV is necessary for the maturation of secretory granules in PC12 cells. 2006

Malika Ahras, and Grant P Otto, and Sharon A Tooze

Cancer Research UK, London Research Institute, London WC2A 3PX, England, UK.

In neuroendocrine PC12 cells, immature secretory granules (ISGs) mature through homotypic fusion and membrane remodeling. We present evidence that the ISG-localized synaptotagmin IV (Syt IV) is involved in ISG maturation. Using an in vitro homotypic fusion assay, we show that the cytoplasmic domain (CD) of Syt IV, but not of Syt I, VII, or IX, inhibits ISG homotypic fusion. Moreover, Syt IV CD binds specifically to ISGs and not to mature secretory granules (MSGs), and Syt IV binds to syntaxin 6, a SNARE protein that is involved in ISG maturation. ISG homotypic fusion was inhibited in vivo by small interfering RNA-mediated depletion of Syt IV. Furthermore, the Syt IV CD, as well as Syt IV depletion, reduces secretogranin II (SgII) processing by prohormone convertase 2 (PC2). PC2 is found mostly in the proform, suggesting that activation of PC2 is also inhibited. Granule formation, and the sorting of SgII and PC2 from the trans-Golgi network into ISGs and MSGs, however, is not affected. We conclude that Syt IV is an essential component for secretory granule maturation.

UI	MeSH Term	Description	Entries
D008561	Membrane Fusion	The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.	Fusion, Membrane,Fusions, Membrane,Membrane Fusions
D006056	Golgi Apparatus	A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough ENDOPLASMIC RETICULUM and directing them to secretory vesicles, LYSOSOMES, or the CELL MEMBRANE. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or Golgi apparatus and fuse with the Golgi, lysosomes or cell membrane. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990)	Golgi Complex,Apparatus, Golgi,Complex, Golgi
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D016716	PC12 Cells	A CELL LINE derived from a PHEOCHROMOCYTOMA of the rat ADRENAL MEDULLA. PC12 cells stop dividing and undergo terminal differentiation when treated with NERVE GROWTH FACTOR, making the line a useful model system for NERVE CELL differentiation.	Pheochromocytoma Cell Line,Cell Line, Pheochromocytoma,Cell Lines, Pheochromocytoma,PC12 Cell,Pheochromocytoma Cell Lines
D050600	SNARE Proteins	A superfamily of small proteins which are involved in the MEMBRANE FUSION events, intracellular protein trafficking and secretory processes. They share a homologous SNARE motif. The SNARE proteins are divided into subfamilies: QA-SNARES; QB-SNARES; QC-SNARES; and R-SNARES. The formation of a SNARE complex (composed of one each of the four different types SNARE domains (Qa, Qb, Qc, and R)) mediates MEMBRANE FUSION. Following membrane fusion SNARE complexes are dissociated by the NSFs (N-ETHYLMALEIMIDE-SENSITIVE FACTORS), in conjunction with SOLUBLE NSF ATTACHMENT PROTEIN, i.e., SNAPs (no relation to SNAP 25.)	SNAP Receptor,SNARE Protein,NSF Attachment Protein Receptor,Receptor, SNAP,SNAP Receptors,SNARE,SNAREs,Soluble N-ethylmaleimide-Sensitive-Factor Attachment Protein Receptor,Target Membrane SNARE Proteins,Target SNARE Proteins,Vesicle SNARE Proteins,Vesicular SNARE Proteins,t-SNARE,tSNAREs,v-SNARE,v-SNAREs,Protein, SNARE,SNARE Proteins, Target,SNARE Proteins, Vesicle,SNARE Proteins, Vesicular,Soluble N ethylmaleimide Sensitive Factor Attachment Protein Receptor,v SNAREs
D050765	Qa-SNARE Proteins	A subfamily of Q-SNARE PROTEINS which occupy the same position as syntaxin 1A in the SNARE complex and which also are most similar to syntaxin 1A in their AMINO ACID SEQUENCE. This subfamily is also known as the syntaxins, although a few so called syntaxins are Qc-SNARES.	Qa-SNAREs,Syntaxin,Syntaxin 10,Syntaxin 10 Protein,Syntaxin 11,Syntaxin 11 Protein,Syntaxin 13,Syntaxin 13 Protein,Syntaxin 17,Syntaxin 17 Protein,Syntaxin 18,Syntaxin 18 Protein,Syntaxin 1A Homologs,Syntaxin 3,Syntaxin 3 Protein,Syntaxin 3A,Syntaxin 3A Protein,Syntaxin 3B,Syntaxin 3B Protein,Syntaxin 3C,Syntaxin 3C Protein,Syntaxin 3D,Syntaxin 3D Protein,Syntaxin 4,Syntaxin 4 Protein,Syntaxin 5,Syntaxin 5 Protein,Syntaxin 6,Syntaxin 6 Protein,Syntaxin 7,Syntaxin 7 Protein,Syntaxin 8,Syntaxin 8 Protein,Syntaxin Protein,Syntaxin Proteins,Syntaxins,Protein, Syntaxin,Protein, Syntaxin 11,Proteins, Syntaxin,Qa SNARE Proteins,Qa SNAREs
D050857	Synaptotagmins	A family of vesicular transport proteins characterized by an N-terminal transmembrane region and two C-terminal calcium-binding domains.	Synaptotagmin,Synaptotagmin 11,Synaptotagmin 12,Synaptotagmin 13,Synaptotagmin 14,Synaptotagmin 15,Synaptotagmin 3,Synaptotagmin 4,Synaptotagmin 5,Synaptotagmin 6,Synaptotagmin 7,Synaptotagmin 8,Synaptotagmin 9,Synaptotagmin III,Synaptotagmin IV,Synaptotagmin IX,Synaptotagmin V,Synaptotagmin VI,Synaptotagmin VII,Synaptotagmin VIII,Synaptotagmin XI,Synaptotagmin XII,Synaptotagmin XIII,Synaptotagmin XIV,Synaptotagmin XV,SytIV Protein,SytVII Protein,SytXIII Protein,Tagmin
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus
D022142	Secretory Vesicles	Vesicles derived from the GOLGI APPARATUS containing material to be released at the cell surface.	SLMVs,Secretory Granules,Synaptic Like Microvesicles,Synaptic-Like Microvesicles,Zymogen Granules,Condensing Vacuoles,Condensing Vacuole,Granule, Secretory,Granule, Zymogen,Microvesicle, Synaptic-Like,Secretory Granule,Secretory Vesicle,Synaptic Like Microvesicle,Synaptic-Like Microvesicle,Vacuole, Condensing,Vesicle, Secretory,Zymogen Granule