Cellular compartment

About: Cellular compartment is a research topic. Over the lifetime, 1082 publications have been published within this topic receiving 53794 citations. The topic is also known as: cell compartmentation.

Localization and translocation of RhoA protein in the human gastric cancer cell line SGC-7901.

Abstract: AIM: To elucidate the localization of RhoA in gastric SGC-7901 cancer cells and its translocation by lysophosphatidic acid (LPA) and/or 8-chlorophenylthio-cAMP (CPT-cAMP). METHODS: Immunofluorescence microscopy was used to determine the localization of RhoA. Western blotting was used to detect both endogenous and exogenous RhoA in different cellular compartments (membrane, cytosol, nucleus) and the translocation of RhoA following treatment with LPA, CPT-cAMP, or CPT-cAMP + LPA. RESULTS: Immunofluorescence staining revealed endogenous RhoA to be localized in the membrane, the cytosol, and the nucleus, and its precise localization within the nucleus to be the nucleolus. Western blotting identified both endogenous and exogenous RhoA within different cellular compartments (membrane, cytosol, nucleus, nucleolus). After stimulation with LPA, the amount of RhoA within membrane and nuclear extracts increased, while it decreased in the cytosol fractions. After treatment with CPT-cAMP the amount of RhoA within the membrane and the nuclear extracts decreased, while it increased within the cytosol fraction. Treatment with a combination of both substances led to a decrease in RhoA in the membrane and the nucleus but to an increase in the cytosol. CONCLUSION: In SGC-7901 cells RhoA was found to be localized within the membrane, the cytosol, and the nucleus. Within the nucleus its precise localization could be demonstrated to be the nucleolus. Stimulation with LPA caused a translocation of RhoA from the cytosol towards the membrane and the nucleus; treatment with CPT-cAMP caused the opposite effect. Furthermore, pre-treatment with CPT-cAMP was found to block the effect of LPA.

Complex formation among rat pancreatic secretory proteins under mild alkaline pH conditions.

Abstract: Previous in vitro studies have demonstrated that enzyme proteins liberated from isolated zymogen granules of the rat pancreas aggregate already at neutral or slightly basic pH and form small particles which in the acidic pH range progressively condense into dense cores of about the size of zymogen granules. To characterize the protein composition of the original particles in more detail non-denaturing agarose gel electrophoresis was employed. Five major protein complexes were identified which upon separation of individual complexes in 1-D or 2-D gel electrophoresis were shown to be composed of a distinct set of known enzymes and several unknown proteins. Complexes 1-4 quickly dissociated when enzyme activation was induced by enterokinase, but complex 5 was resistant even to this treatment. All 5 complexes revealed a distinct fine structure when eluted from the gels and studied in negative staining electron microscopy. These findings suggest that pancreatic zymogens form complexes already in the lumen of the rough endoplasmic reticulum and are transported as such to the Golgi complex where they aggregate into granule cores due to the internal acidic pH. Complex formation may thus facilitate zymogen sorting within the rough endoplasmic reticulum and may prevent premature enzyme activation within cellular compartments.