9.21-9.25

Question 1

what does hnRNP stand for

Answer 1

heterogeneous nuclear ribonucleoprotein particle

Question 2

what are hnRNPs

Answer 2

complexes of pre-mRNA associated with proteins

Question 3

function of hnRNPs

Answer 3

involved with RNA folding so it can be processed

Question 4

are 5’cap and Poly-A tail proteins hnRNPs

Answer 4

no

Question 5

only __________ and __________ processed mRNAs are exported usually

Answer 5

completely, correctly

Question 6

ex. of mRNAs that are exported before processing

Answer 6

• Hac1p
• viral genomes (HIV)

Question 7

HIV exporting RNA genome without intron removal

Answer 7

• HIV produces protein REV
• REV binds to RRE (REV response element) on unspliced HIV-1 mRNA
• REV has NES, exports out of nucleus

Question 8

ex. of constitutive mRNA

Answer 8

• ribosomal protein
• cytoskeletal fiber protein

Question 9

ex. of regulated mRNA

Answer 9

heat shock response and poly A+ RNAs

Question 10

processing associated with transcription:

Answer 10

1. 5’ 7-methylGuanosine cap (occurs while RNA pol II not much farther along
2. splicing - during transcription
3. Poly-A tail - occurs after 3’ end is generated by endonuclease (RNA pol hasn’t stopped yet)

Question 11

what adds poly-A tail

Answer 11

Poly-A polymerase

Question 12

after splicing, what proteins will be on mRNA?

Answer 12

• EJC (exon junctional complex) remains bound to exon/exon splice site
• EJC includes Aly - interacts with spliceosome and TAP
• TAP - binds to FG repeats and can have karyopherin activity

Question 13

after proteins on mRNA, it is considered

Answer 13

mRNP (messenger ribonucleoprotein particle)

Question 14

what is an exosome made up of

Answer 14

ribonucleases

Question 15

exosome

Answer 15

complex of ribonucleases located near tcr sites that degrades mRNAs processed incorrectly

Question 16

what is likely involved in the removal of mRNP proteins?

Answer 16

Dbp5 - essential mRNA export protein

Question 17

DEAD-box proteins

Answer 17

hydrolyze ATP, function in mRNA metabolism

Question 18

RNA of snRNP

Answer 18

U snRNA

Question 19

what is U snRNA made by

Answer 19

RNA polymerase II

Question 20

modification of U snRNA at first in nucleus

Answer 20

addition of 5’ 7-meGuanosine cap

Question 21

what does 5’ 7-meGuanosine cap serve as in U snRNA

Answer 21

signal to cytoplasm

Question 22

modification of U snRNA in cytoplasm

Answer 22

• methylated (x2) to make trimethyl-G cap
• associated with other proteins to form U snRNP complex

Question 23

what brings U snRNP back into nucleus

Answer 23

• snurportin
• importin B

Question 24

modification of U snRNP in nucleus

Answer 24

addition of more proteins in Cajal bodies and GEMS

Question 25

what transcribes microRNAs

Answer 25

RNA polymerase II in nucleus

Question 26

where are micorRNAs usually found

Answer 26

introns of protein-coding genes or intergenic regions

Question 27

what are miRNAs important for

Answer 27

development, differentiation, apoptosis

Question 28

where do miRNAs bind to target mRNA

Answer 28

cytoplasm

Question 29

role of miRNA with mRNA

Answer 29

blocks tsl, can promote mRNA degradation

Question 30

processing steps of miRNA

Answer 30

- precursor in nucleus processed by Drosha (Pasha) - exported by exportin - Dicer further processes to yield functional miRNA