Analysis of Protein Localization and Secretory Pathway Function ..
Protein synthesis involves a number of steps: 1
Steps involved with protein synthesis: ..
Basolateral-specific transport pathways are also thought to play key roles in polarized cells. The best studied of these pathways in is in the transport of the EGF-receptor in the vulval precursor cells (VPCs; see ). is normally restricted to the basolateral membrane of the VPCs, a process that requires the PDZ-domain proteins , , and (). The /7/10 complex binds directly to the intracellular domain, and is therefore likely to function as a sorting factor, directing to the basolateral membrane during secretion and/or after endocytosis and recycling (). The protein has been shown to associate with an intracellular compartment on or near the Golgi consistent with a role in protein sorting during secretion ().
Do H, Lee WS, Ghosh P et al. (2002) Human mannose 6‐phosphate‐uncovering enzyme is synthesized as a proenzyme that is activated by the endoprotease furin. Journal of Biological Chemistry 277: 29737–29744.
Protein Synthesis -Translation and Regulation
Some genes are involved in stallion semen tolerance to cryopreservation. This work evaluated the relationship between CRISP-3 protein and some of its single nucleotide polymorphisms, with post-thawing semen quality in stallions. This study demonstrated that different parameters of seminal quality are influenced by the CRISP-3 genotype and the concentration of this protein in seminal plasma.
Signalling pathways responsible for follicular activation in the mare remain uncharacterised. Messenger RNA expression and protein localisation of members of the PI3K/AKT and JAK/STAT pathways were analysed using tissue from fetal and adult mare ovaries. Findings suggest that members of these pathways are indeed present and may serve as useful biomarkers for assessment of ovary development in the horse.
Unfolded protein response - Wikipedia
Female sperm storage is known across many animal phyla, but the mechanism(s) remains elusive. Using the Indian garden lizard, Calotes versicolor as a model, we identified a unique abundant protein of ~55-kDa in the uterovaginal region that controls the motility of the spermatozoa. These studies are likely to unravel the secrets of sperm storage.
All of the ectodermal epithelial-like cells are known to require the transcription factor to aquire their final differentiated forms (). In particular it is the apical membrane domain that appear most severely affected in mutant ectodermal epithelia. has therefore been proposed to regulate the expression of gene products that form and maintain apical epithelial character. Screens for mutants with Lin-26-like defects could therefore identify apical-specific trafficking factors. Michaux et al () took just this approach and identified , a predicted 12-pass transmembrane protein required for the function of these cell-types. mutants displayed defects in the hypodermis, excretory canal, vulva, rectum and amphids and phasmids. In mutants vesicles and amorphous material accumulate near the apical surface of the affected cells suggesting that secretion is defective. contains a sterol-sensing domain, a type of domain found in proteins such as Dispatched, Patched and PC1 that are involved in cholesterol associated trafficking processes. A rescuing ::GFP reporter is localized to the apical surface of epithelial cells that require function, consistent with such a proposed function ().
Protein folding in the endoplasmic reticulum Protein synthesis
Cholesterol: Synthesis, Metabolism, Regulation
ER stress and the unfolded protein response - …
Difficult to Express Proteins - Protein Engineering Summit
In eukaryotic cells the ER is the first compartment in the secretory pathway
Metabolism – Proteins | Biochemistry for Medics – …
Cytosol - Wikipedia
Urea is the end product of nitrogen metabolism
Another class of proteins thought to function in secretion are those related to the putative hedgehog receptor Patched. Kuwabara and colleagues have identified 29 patched (PTC) or patched related (PTR) genes in the genome, each of which encodes a predicted multipass transmembrane protein with a predicted sterol-sensing domain (). The phenotypes of mutants indicate a likely defect in the secretory pathway and in germline cytokinesis in particular. The presence of such a large and diverse family of these proteins in could indicate diverse functions in membrane trafficking processes ().
Quick revisions | Biochemistry for Medics – Lecture Notes
One component of the general secretory pathway that has been studied in significant detail in is , a part of the endoplasmic reticulum vesicle coat complex known as COPII (). COPII is known to be the primary vesicle coat complex used in yeast and mammalian cell transport from the ER to the Golgi. Roberts et al. identified a single mutant allele of in a screen for embryonic lethals defective in cuticle synthesis as assayed by a cuticle collagen reporter, (). These authors went on to show severe defects in cuticle synthesis in mutants resulting in accumulation of collagen intracellularly, presumably in the ER. Zygotic embryonic lethality during elongation was found in homozygous mutants derived from heterozygous mothers. Normal progression through early development presumably relies upon maternally derived . RNAi experiments revealed a requirement for during larval development, particularly during molting. Adults depleted of by RNAi also showed severe germline defects including binucleate oocytes, lack of yolk uptake by oocytes resulting from a failure of yolk receptors () to reach the cell surface, and premature maturation/partitioning of individual germ cells, possibly resulting from loss of cell surface receptors in the distal gonad. A partially functional ::GFP reporter gene indicated that is broadly expressed at all life stages, and that in hypodermal cells the protein is concentrated in distinct foci. In the embryonic hypodermis these foci were enriched apically at the periphery of the endoplasmic reticulum. These positive foci likely represent ER exit sites where newly synthesized cargo molecules concentrate and are packaged into COPII coated vesicles for delivery to the Golgi.
Chapter 07 - Membrane Structure and Function | …
As in other eukaryotes cells possess an endoplasmic reticulum into which most membrane or secretory proteins are inserted co-translationally. Some lumenal ER-resident proteins are retained in the ER by KDEL or HDEL signals in their extreme C-termini. cells also possess Golgi stacks, the next organelle through which secretory proteins pass. Unlike mammalian cells, invertebrates such as have many small "mini stacks" throughout the cytoplasm of most cells rather than one large stack positioned near the nucleus. From the Golgi, secretory proteins and some membrane proteins proceed to either the plasma membrane or to the endosomal system, depending upon various signals embedded in the primary sequence of the proteins. does not possess any obvious homologs of the mannose-6-phosphate receptors, and so may not use the mannose-6-phosphate system for tagging and sorting newly synthesized lysosomal hydrolases. Worms may instead use amino acid based signals and a vps10/sortillin receptor type system for such sorting, as is known to be the case in yeast.
The GLUT4 Glucose Transporter - ScienceDirect
Gillece P, Luz JM, Lennarz WJ et al. (1999) Export of a cysteine‐free misfolded secretory protein from the endoplasmic reticulum for degradation requires interaction with protein disulfide isomerase. Journal of Cell Biology 147: 1443–1456.
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