Chapter 8; protein localization

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RNA: The major substrate for nuclear export is [protein, RNA, importins]
di: Importin alpha-beta is a(n) [n]mer.
120: The overall diameter of the nuclear pore structure (not the pore itself) is approximately [n] nm in diameter.
10; leucine: The nuclear export sequence (NES) consists of a [n] amino acid sequence featuring a pattern of conserved [amino acid].
is not: The addition of a single ubiquitin unit [is, is not] sufficient to trigger degradation by the proteasome.
yes: Do the SRP and SRP receptor BOTH have GTPase activity?
phobic: Protein folding is driven by the aggregation of hydro....... sequences.
40: Motifs which bind to the Hsp70 chaperone occur approximately every [number] amino acids.
direction of transport: Ran is important in the control of [transport receptor specificity, direction of transport, opening and closing of nuclear pores].
GTP: Nuclear export complexes are stabilized by the [GTP, GDP]-bound form of Ran.
E3: Specificity of ubiquitination usually depends on selectivity of the [E1, E2, E3] species.
alpha helix; amphipathic: The organelle protein leader sequence forms a [secondary structure] which is [basic, amphipathic, acidic, hydrophillic].
Sec61: The segment of the translocon which interacts with the ribosome to form a seal during translocation is [name of subunit]
positive: Regions at the margins of internal signal-anchor sequences carry [positive or negative] charges.
KDEL; C: Proteins targeted to the ER contain the sequence [tetrapeptide sequence] at their [N or C] terminal.
cross: Chloroplast proteins targeted to locations within the thyalkoid lumen [cross, do not cross] the stroma en route.
signal recognition particle: Attachment of a translating ribosome to the ER requires the protein [protein name; not an acronym]
both directions: Nuclear transport occurs in [one direction, both directions].
20; 26: The archaeal proteasome exists in a smaller [n]S form and a larger [n]S form.
E3: Elongation of the ubiquitin chain is carried out by [E1, E2, E3].
yes: Can a single protein feature both an NES and an NLS?
E2; E1; E2: [E1, E2, E3] is referred to as the ubiquitin-conjugating protein; it transfers ubiquitin from [E1, E2, E3] to [E1, E2, E3, the substrate protein].
chaperones: Proteins which cannot renature into an active conformation require:
are: The three classes of RNA [are, are not] each transported by their own system of proteins.
transport receptor: The analog of the SRP in nuclear import is the [protein name]; it binds both the nuclear pore and the cargo protein.
N: In group I transmembrane proteins, the [N or C] terminus faces the extracellular space.
E3, E2: [E1, E2, E3], or ubiquitin ligase, transfers ubiquitin from [E1, E2, E3] to the substrate protein.
proline: The amino acid [name of amino acid] is often located in the upstream portion of the NLS.
internal: Group II transmembrane proteins have a(n) [terminal, internal] signal sequence.
self-assembly: The ability of a denatured protein to renature into an active form is called:
true: The nuclear localization sequence is unconserved. True or false?
can: Nuclear export or import by a specific pathway [can, cannot] be saturated.
cotranslational: Translocation in which a nascent protein associates with the translocation apparatus while still attached to the ribosome
translocation: The process of inserting a protein into or passing a protein through a membrane:
shuttle between nucleus and cytosol: Poly-a tail binding proteins [remain in the cytosol, remain in the nucleus, shuttle between nucleus and cytosol].
occluded; open: The eukaryotic proteasome's center [open, occluded]; the archaeal proteasome's center is [open, occluded].
different from: In the eukaryotic proteasome, all alpha and all beta subunits are [the same as, different from] all others.
cytoplasmic: More positively charged residues are found on the residues on the [cytoplasmic or luminal] side of the anchor.
76; covalent bond: Ubiquitin is a [n]-residue long protein which is linked to substrates by a(n) [ionic interaction, covalent bond, disulfide bridge].
philic; phobic: The surface of a protein is generally hydro........; the lipid core of a membrane is hydro........
E1: The ubiquitin-activating protein [E1, E2, E3] links itself to ubiquitin.
acidic, basic: The organelle targeting sequence contains both [acidic,uncharged] and [basic, aromatic, modified] amino acids.
GDP: Nuclear import complexes are stabilized by the [GTP, GDP]-bound form of Ran.
70: The translocon pore is closed/sealed until the peptide is [n] amino acids in length.
lysosome: Ubiquitinated plasma-membrane proteins are degraded by the [name of agent].
true: All protein is synthesized in the cytosol, and all RNA is synthesized in the nucleus. True or false?
Pex5p: Peroxisome proteins bearing the sequence designated PTS1 are imported with the help of [protein name].
CAS: Importin alpha, when located in the nucleus, is bound by [protein name], which functions as an exportin.
Hsp90: ....... is a chaperone protein involved in signal transduction (i.e. steroid receptors and signaling kinases).
N: Cotranslationally translocated peptides are generally targeted by [N or C] terminal sequences.
SRP; SRP receptor: Attachment of a translating ribosome begins with recognition of the signal sequence by the [protein], which binds to the membrane-associated protein [protein name].
46, lys: Subsequent ubiquitins are linked to the chain at position [n], which is the amino acid [3-letter code].
are not: All NLS sequences [are, are not] composed of a single, uninterrupted stretch of basic amino acids.
yes: Do combined signal-anchor sequences resemble cleavable signal sequences?
nuclear pore; cargo NLS: Importin alpha-beta's beta subunit binds to the [nuclear pore, cargo NLS], while its alpa subunit binds to the [nuclear pore, cargo NLS].
signal peptidase: The [name of protein] cleaves the signal sequence from the peptide after translocation.
7; or: Each of the proteasome's four 'rings' consists of [n] alpha [and, or] beta subunits.
N: In group II transmembrane proteins, the [N or C] terminus faces the cytoplasm.
eight: The nuclear pore consists of inner and outer ring structure with [n]fold symmetry.
10: The actual pore created by the nuclear pore is [n] nm in diameter
15 to 30; phobic: Cotranslational insertion is directed by a signal sequence which is [range of numbers] amino acids, consisting largely of hydro[phillic or phobic] amino acids.
anchor: In Group II transmembrane proteins, the singal sequence is combined with a(n) ......... sequence.
single proteins: The transport receptors importin-beta3 and transportin are [single proteins; multi-subunit complexes].
3 to 4; C: The signal for transport to the peroxisome is [number] amino acids long, and located at the [N or C] terminus.
25: Mitochondrial and chloroplast proteins are targeted to their respective membranes with [~number] amino acid sequences.
4 to 9; basic: The nuclear localization signal is [number] amino acids long; it is composed of [electronic character] amino acids.
anchoring in the membrane: The eight 'arms' of the nuclear pore may be responsible for [anchoring in the membrane, other options]
GDP; GAP: Ran-[GTP, GDP] is found in the cytosol, due to the activity of [GEF, GAP].
12: Ion channels typically have [number] alpha-helical transmembrane domains.
GTP; GEF: Ran-[GTP, GDP] is found in the nucleus, due to the activity of [GEF, GAP].
beta: The [alpha, beta, alpha and beta] subunits of the archaeal proteasome have protease activity.
Chaperonin: Unlike the Hsp70 system, the ............. system consists of a large oligomeric "cage" which provides an environment conducive to correct folding.
short, basic: The nuclear localization sequence is [short, long] and contains [basic, acidic, aliphatic] residues
cap-binding complex: The export protein active for snRNAs is the [protein name]
no: Are ribosomes attached to the rough ER a distinct species from those operating in the cytosol?
the same: The nucleus and the cytoplasm are separated by nuclear pores, which help to maintain the nucleus and cytosol in [the same, different] ionic conditions.
false: The cotranslational targeting sequence is retained in the mature protein. True or false?
Sec61; tri: The translocon's pore is formed by the subunit [name of peptide]; it is a(n) [n]mer.
plasma membrane: The 'default' sorting pathway ultimately leads to the:
GroEL/GroES; TRiC: The two chaperonin systems are [present in all organisms] and [present in the eukaryotic cytosol].
beta: Single-protein transport receptors most resemble the [alpha, beta] subunit of importin alpha-beta.
true: Misfolded proteins can be ejected from the ER to be degraded in the cytoplasm. True or false?
false: True or false: the organelle targeting sequence is highly conserved across all eukaryotic organisms.
Hsp40; GrpE: The components of the Hsp70 system are Hsp70, ........ and ......
matrix: The default destination for mitochondrial proteins is the [outer membrane, intermembrane, matrix, inner membrane].
BiP: [name of protein] acts as a molecular ratchet on the luminal side of translocon, preventing the nascent polypeptide from 'slipping' backwards.
open; closed: The translocon is an aqueous channel through the ER membrane; before ribosome binding, it is [open/closed] at the cytosolic face and [open/closed] at the luminal face.
7: G-protein coupled receptors have [number] transmembrane domains.
unconserved: The nuclear localization sequence is [conserved, unconserved].
cytosol, folded: Once Pex5p or Pex7p is bound to a peroxisome-targeted protein located in the [cytosol, ER], the protein is imported into the peroxisome in its [folded, unfolded] conformation.
opposite: An odd number of membrane-spanning domains implies that the N and C termini face the [same, opposite] side(s) of the membrane.
cleavage, is: The mitochondrial leader sequence is modified by [prenylation, acylation, phosphorylation, cleavage, association with chaperone proteins] if the protein [is, is not] intended for a location other than the matrix.
true: Chaperones are responsible for maintaining proteins in an unfolded state prior to transport. True or false?
requires; requires: Nuclear import [requires, does not require] a carrier protein; nuclear export [requires, does not require] a carrier protein.
mannose-6-phosphate: Proteins targeted to the lysozome have a [molecule] tag.
Pex7p: Peroxisome proteins bearing the sequence designated PTS2 are imported with the help of [protein name].

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