Splicing is an SN2 reaction that proceeds through a pentavalent phosphorous intermediate.

TLS Online TPP Program

#Id: 7780

#Unit 2. Cellular Organization

A set of seven structural nucleoporins forms a Y-shaped structure about the size of the ribosome, known as the Y complex.

TLS Online TPP Program

#Id: 7781

#Unit 2. Cellular Organization

A structural motif repeated several times within the Y-complex is closely related to a structure found in the COPII proteins that drive the formation of coated vesicles within cells.

TLS Online TPP Program

#Id: 7782

#Unit 2. Cellular Organization

Nucleoporin

Large group of proteins that make up the nuclear pore complex. one class (FG-nucleoporins) participates in nuclear import and export.

TLS Online TPP Program

#Id: 7783

#Unit 2. Cellular Organization

FG-nucleoporins, the central channel of the NPC filled with a fluidlike phase that allows the diffusion of small molecules while excluding unchaperoned hydrophilic proteins larger than 40 kDa.

TLS Online TPP Program

#Id: 7784

#Unit 2. Cellular Organization

All proteins found in the nucleus, histones, transcription factors,  DNA & RNA polymerases are synthesized in the cytoplasm and imported into the nucleus through nuclear pore complexes.

TLS Online TPP Program

#Id: 7785

#Unit 2. Cellular Organization

These proteins contain a nuclear-localization signal (NLS) that directs their selective transport into the  nucleus.