Navigation Links
Splicing (genetics)


In genetics, splicing is a modification of genetic information prior to translation.

In eukaryotes, a gene often contains altering sequences known as exons (expressed codons) and introns (interrupting codons). In contrast to prokaryotes, which do not usually have introns, eukaryotes initially create a primary mRNA transcript called pre-mRNA that is composed of both introns and exons (see transcription). Pre-mRNA has to be spliced before it can be translated into protein. During splicing, the introns are removed from the mRNA using one of three methods:

  • Protein-mediated: spliceosomes, huge molecular structures composed of small nuclear ribonuclear proteins (snRNPs (pronounced "snurps")), splice the 3' end of the first exon, form the intron into a lariat, splice the 5' end of the next exon, and fuse the exon-exon junction;
  • Self-splicing: specialized introns serves as ribozymes, performing the functions of the spliceosome intramolecularly;
    • Group 1: do not form lariats but instead bind introns to free-floating guanine;
    • Group 2: perform the same two-step chemical reaction as the protein-mediated reaction (these are thought to be the evolutionary precursor to the much more common spliceosome).

Regardless of which process is used, the excised lariats are discarded. The final mRNA product must have each of the following:

  • A 5' cap, a guanine triphosphate nucleotide, thus named because it binds to the 5' end of the mRNA;
    • The methylated cap prevents the 5' end from being degraded by exonucleases
  • A leader that follows the 5' cap but precedes the exons;
  • A trailer that follows the exons;
  • A poly-A tail that follows the trailer;
    • The poly-A tail serves as a stalling mechanism; when exonucleases begin to degrade the 3' end, the long trail of extra As takes extra time to degrade, elongating the mRNA's lifespan.

Mutations in the introns can prevent splicing and thus prevent protein biosynthesis.

In many cases, the splicing process can create many unique proteins from a large collection of exons. This phenomenon is called alternative splicing.

XXXXEEEEIIIEEEEEEEEEEIIIIEEEEEEEEEEXXXX   DNA with exons and introns
           ↓transcription↓
    EEEEIIIEEEEEEEEEEIIIIEEEEEEEEEE       mRNA (primary transcript) with exons and introns
           ↓  splicing   ↓
    CLLLEEEEEEEEEEEEEEEEEEEEEEEETTTTAAAA  mRNA (spliced) with exons, 5' cap, leader, trailer and poly-A tail
           ↓ translation ↓
             polypeptide
See also : genetics -- cDNA


'"/>


(Date:7/31/2015)... 31, 2015 NXT-ID, Inc. (NASDAQ: NXTD ) ... on the growing mobile commerce market and creator of ... provisional patent 62/198989 for ELECTRONIC CRYPTO-CURRENCY MANAGEMENT ... method to advance crypto-currencies such as Bitcoin into the ... uniform way to manage all payments.  ...
(Date:7/23/2015)... 2015 Aware, Inc. (NASDAQ: AWRE ), a ... results for its second quarter ended June 30, 2015.  ... $4.5 million, a decrease of 33% compared to $6.8 million ... second quarter of 2015 was $0.3 million, or $0.01 per ... diluted share, in the same period a year ago.  ...
(Date:7/20/2015)... , July 20, 2015  Acuity Market Intelligence,s ... The Convergence of Commerce and Privacy" forecasts that ... biometric apps will be downloaded to smart mobile ... mobile biometrics market is projected to generate more ... during the seven-year forecast period.    ...
Breaking Biology News(10 mins):NXT-ID Patents Electronic Crypto-Currency Management Technology 2NXT-ID Patents Electronic Crypto-Currency Management Technology 3NXT-ID Patents Electronic Crypto-Currency Management Technology 4Aware, Inc. Reports Second Quarter 2015 Financial Results 2Aware, Inc. Reports Second Quarter 2015 Financial Results 3Aware, Inc. Reports Second Quarter 2015 Financial Results 4Aware, Inc. Reports Second Quarter 2015 Financial Results 5Aware, Inc. Reports Second Quarter 2015 Financial Results 6Biometrics on Smart Mobile Devices to Redefine Digital Identity with 12.9 Billion Biometric App Downloads between 2014 and 2020 2
... is the role of the research university today center ... ground for future leaders?, Are research universities prepared for the ... falling behind in the global innovation race? , People are ... flowing? , What is the impact of the fiscal crisis ...
... the Franconian Jura evokes associations with a pet cemetery, for ... It also poses an intriguing question: Were all dinosaurs dressed ... newly hatched when it met its end, is remarkable in ... the dinosaur fossil record, so every new discovery provides insights ...
... of Nottingham are leading research that will develop the world,s ... with colleagues in South Korea, the project aims to build ... taking into account the differences and variations which occur from ... could be used to help doctors in countries like South ...
Cached Biology News:All Things Research 2012 roundtable discussion 2Feathered saurians -- downy dinosaur discovered 2Road-mapping the Asian brain 2
Other biology definitionOther Tags