what is protein localization?

Answer 1

Or, in layman's terms, protein localization is the process of determining where in the cell a protein is located (for example, in membranes, in the nucleus, in mitochondria, etc...).

This is often done by labelling the protein with a flourescent tag (like GFP) and looking at cells under a microscope.

Answer 2

There is an ever-increasing number of genes that have been sequenced but are of completely unknown function. The ability to determine the location of such gene products within the cell,
protein localization
either by the use of antibodies or by the production of chimeras with green fluorescent protein, is a vital step towards understanding what they do. This is one major reason why fluorescence microscopy is enjoying a revival. This guide provides detailed, practical advice on all aspects of the subject: from choosing the right equipment, to interpreting results. It balances the advantages of a wide range of techniques-- including live cell work--against the potential pitfalls, offering invaluable "tricks of the trade" along the way.

Answer 3

(m)

Among the greatest challenges facing biology today is the exploitation of huge amounts of genomic data, and their conversion into functional information about the proteins encoded. The German cDNA Consortium is providing a sequence validated ORF resource, encoding novel proteins of completely unknown function. This consortium clones ORFs into vectors allowing to express N- and C-terminal fusions with the green fluorescent protein (GFP).

As a first step towards the characterization of proteins we examine their subcellular localizations in living cells (Wiemann et al., 2004, Simpson et al., 2000). This data allow us to classify the proteins into subcellular groups, determining the next steps towards a detailed functional characterization.

We have thus far localized over 1,000 different proteins in living cells, employing 4,000 different expression constructs. The localization data in many cases are the first functional information for these proteins, helping to identify targets to be funnelled into high throughput functional assay projects of SMP-Cell.



An ORF and protein-tracking database was developed, which has been expanded to the LIFEdb web-database where bioinformatic and functional (e.g. localization, cellular assays) data are made public.

Answer 4

each protein in a body has a unique role to play, as we know body works on signal transduction mechanism i.e. the produced protein will go to its position due to gathering signals from that perticular site. so each protein has a receptor at a perticular position, hence the mobility or process of carrying the produced protein to a specific place is called as localisation of protein

Answer 5

Some constraints upon localization are dictated by the nature of the hormone-binding site. In the plant Arabidopsis, the ethylene receptor family is composed of five members: ETR1, ERS1, ETR2, ERS2, and EIN4 (4). Of these receptors, the ethylene receptor ETR1 has been characterized in most detail because it was the first member of the receptor family identified (5, 6). Analysis of the primary amino acid sequence of ETR1 indicates that there are three predicted transmembrane domains located near the amino terminus: a GAF domain, a histidine kinase domain, and a receiver domain. GAF domains are involved in cGMP binding and light regulation in other proteins, but the function of the GAF domain in ETR1 is unknown (7). Histidine kinase and receiver domains are signaling elements originally identified as components in bacterial phosphorelays and are now ... known to be present in plants, fungi, and protists (8). Source:
jbc.org
Helpful | Not Helpful feedback submitted Subcellular localization of the Poa semilatent virus cysteine-rich b protein was studied by using different approaches. In infected tissue, b was detected mainly in the P30 fraction as monomers, dimers and oligomers. Green fluorescent protein-fused b was found to localize in punctate bodies in the cytoplasm. Colocalization with marker proteins demonstrated that these bodies represent peroxisomes. Immunoelectron microscopy revealed that b was localized in the peroxisomal matrix and that localization of b in peroxisomes required the C-terminal signal tripeptide SKL. An SKL-deletion mutant exhibited a diffuse localization, but retained the protein's ability to suppress RNA silencing, determine infection phenotype and support virus systemic spread. Source:
vir.sgmjournals.org
Helpful | Not Helpful feedback submitted ER localization presents several advantages for signal transduction. It is energetically efficient, as the receptor is not exported all the way through the secretory system to the plasma membrane. Receptors are rapidly delivered to their site of action, which may be important for members of the Arabidopsis ethylene receptor family such as ERS1, ERS2, and ETR2 whose expression is induced by ethylene (12). It ... potentially allows for local regulation of ER-based processes such as Ca2+ release and protein secretion, Ca2+ having been previously implicated in plant ethylene responses (34-36). ETR1 could also potentially interact with the membrane-associated proteins RAN1 and EIN2 (37-39), both of which are implicated in ethylene signal transduction but whose subcellular localization is unknown. RAN1 is a copper transporter thought to deliver the copper co-factor required for ethylene binding by the receptors (37, 39). Source:
jbc.org
Helpful | Not Helpful feedback submitted The reasons for this differential localization are not readily apparent. One implication of these findings is that in response to allergen sensitization and challenge, different profiles of chemokines develop, affecting leukocyte recruitment to distinct inflammatory sites. Among the chemokines that may directly affect the pattern of eosinophil accumulation are eotaxin, regulated on activation normal T cells expressed and secreted (RANTES), macrophage inflammatory protein-1, and monocyte chemoattractant protein-5 (8, 15, 16, 27). The effects may ... be indirect, mediated by differential expression, for example, of monocyte chemoattractant protein-1, which is clearly modulated during allergic lung inflammation (9). Studies are currently underway to examine chemokine expression and localization in these two informative strains of mice. Furthermore, in the absence of in situ markers of eosinophil activation, it is unclear how the pattern of eosinophil distribution in the lung affects readouts of airway responsiveness in response
The increased localization of type IV collagen, laminin, and fibronectin in DEX plus ascorbate treated cells is apparently not due to increased accessibility of these proteins to antibody detection. No changes in cell shape or separation of neighboring cells that might expose matrix proteins found on the basal surface of individual cells are seen in cultures treated with both reagents relative to untreated cells (not shown). Source:
iovs.org
Helpful | Not Helpful feedback submitted Subcellular localization is currently predicted using four different methods: predictNLS (nuclear localization signal), LOChom ( using homology ), LOCkey (using keywords) and LOCtree (prediction based on hierarchical support vector machines). The reported localization is based on the method which predicts localization of a given protein
Regulation of MAPK localization is critical for signaling and is required for activation of nuclear targets. In mammalian cells, when ERK1/2 is prevented experimentally from entering the nucleus, phosphorylation of the transcription factor, ELK1, in the nucleus is disrupted, and reinitiation of DNA synthesis is blocked, whereas activation of cytosolic substrates is unperturbed (49). The mechanism by which dynamic localization of MAPK is achieved is complex. Taken together, studies from yeast and mammalian cells suggest that changes in MAPK localization are caused by changes in its interaction with a host of different nuclear and cytosolic proteins rather than through a direct regulation of its rate of nuclear import and/or export. Source:
jbc.org
Helpful | Not Helpful feedback submitted Cdc23-GFP appears to maintain its nuclear and nuclear spot localization during most of the cell cycle, but is visible on the spindle in anaphase. This spindle localization would position the APC/C for a "wave of proteolysis" as seen with cyclin B in Drosophila embryos (HUANG and RAFF 1999). It is possible that certain substrates are specifically shuttled to the spindle for ubiquitination, as in the case of mammalian cyclin B1 (CLUTE and PINES 1999). However, elimination of the spindle association of the motor protein Kip1p does not appear to prevent its ubiquitination (GORDON and ROOF 2001). Although the association of an APC/C substrate with the spindle may not be essential for ubiquitination, the timing and specificity of ubiquitination may be altered if substrates are not properly targeted to the APC/C. Source:
genetics.org
Helpful | Not Helpful feedback submitted Human NPM3 is an abundant and widely expressed protein with primarily nuclear localization. These biological activities, together with its physical relationship to the chaparones nucleoplasmin and nucleophosmin, are consistent with the proposed function of NPM3 as a molecular chaperone functioning in the nucleus. Source:
biomedcentral.com
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