Nuclear Transport Flashcards
The nuclear envelope is continuous with what other cellular structure?
endoplasmic reticulum
What provides cytoskeletal support to the nucleus?
nuclear lamina
What structure controls traffic between nucleus and cytoplasm?
nuclear pores
What is the site of ribosomal RNA transcription and processing in the nucleus?
Nucleolus
Two functions of the nuclear lamina
1) provides structural and functional support to the nucleus
2) binds chromatin and other nuclear proteins
What is the nuclear lamina made up of?
A class of intermediate filaments called lamins
Which two types of lamin are made up of a single gene which is alternatively spliced?
Lamin A and Lamin C
Which lamin(s) have their farnesyl group cleaved off?
Lamin A and Lamin C
Which lamin(s) keep their farnesyl group?
Lamin B1 and B2
What differs between Lamin A and Lamin C?
Lamin C has the final 133 AAs at the C-terminus removed (well they’re never translated more so)
Which lamin(s) are expressed in all cells?
Lamin B1 and Lamin B2
Which proteins bind Lamin B1/B2 to the inner nuclear membrane?
Emerin and Lamin B Receptor (LBR)
What connects the nuclear lamina with the cytoskeleton
LINC complex
Three roles of LINC complex
nuclear migration, nuclear integrity, and chromosome movement during cell division
What proteins make up the nuclear pore complex?
nucleoporins
The nuclear pore complex has a basket-like complex on which side?
nucleus
What forms the basic structural scaffold around the nuclear pore complex?
Y-complex
What line the central channel of the nuclear pore complex
FG-nucleoporins
Why is it called a FG-nucleoporin?
it has hydrophillic repeats with hydrophobic FG (phenylalanine-glycine)
Which signal is required to bring something into the nucleus?
Nuclear Localization Signal (NLS)
Which signal is required to take something out of the nucleus?
Nuclear Export Signal (NES)
Which nuclear transport signal has basic amino acid sequences (Lys-Arg). Also just lysine rich sequences as well
Nuclear localization signal (NLS)
Which nuclear transport signal has leucine rich sequences?
Nuclear export signal (NES)
The nuclear localization signal (NLS) binds which transport protein?
importin
The nuclear export signal (NES) binds which transport protein?
exportin
Name two ways that nuclear import can be inhibited
1) ikB binds to NLS
2) NLS is phosphorylated directly
Guanine nucleotide binding protein with GTPase activity
Ran
Exchanges Ran GDP for GTP in nucleus
Guanine Nucleotide Exchange Factor (GEF)
Facilitates hydrolysis of Ran’s GTP in the cytoplasm
RAN GTPase Activating Protein (GAP)
Nucleus to Cytoplasm Transport
Ran-GTP
Cytoplasm to Nucleus Transport
Ran-GDP
What binds to mRNA-protein complexes (mRNPs) for Ran-independent export?
NXF1/NXT1 complex
What’s the RNA helicase with ATPase activity in the cytoplasm which removes NXF1/NXT1 complex in Ran-independent export?
Dbp5
A defect in emerin and lamin A/C
Emery-Dreifuss Muscular Dystrophy
Premature aging. Defect in LMNA gene. Defective Lamin A/C. Abnormal nucleus.
Hutchinson-Gilford Progeria
What’s the gene defect in Hutchinson-Gilford Progeria?
Single base mutation activating a cryptic mRNA splice cite. Shorter lamin protein and the farnesyl stays attached.
