Discussion 10: Signaling
MCB 150
Directions: Fill out the table involving transport to various cellular locations. The beginning and ending locations have been provided. The table continues on the
next page.
Starting
point
Cytoplasm
Nucleus
Cytoplasm
Ending Point
Type of molecule
(for example:
amino acid, lipid,
nucleic acid etc.)
Amino acid
sequence
Signal(s) presented
Location of
translation
NLS
Cytoplasm
NES
Cytoplasm
Amino acid
sequence
Internal Signal
Sequence, or
Amino terminal
Signal Sequence
(Signal sequence is
okay)
RER
Amino acid
sequence
Nucleus
Cytoplasm
ER
5
Location and/or
arrangement of signal
(more specific than the
previous column)
Part of the incoming
protein (or a protein
buddy that binds to the
imported molecule), could
be bipartite, or not (also
remember certain proteins
can get though without
NLS, such as RAN)
Part of the protein
sequence (or a protein
buddy that binds to the
exported molecule), or
could be a sequence that
is presented on the folded
protein (certain proteins
such as shuttle proteins
and RAN can get though
without NES)
Part of the protein
sequence, either on the
amino terminus or internal
Key
characteristic of
the signal
Basic/positively
charged: often
includes a proline
Leucine rich
Hydrophobic
amino acids
*(see note at
Bottom)
Examples
Ribosomal proteins,
transcription factors, DNA
polymerases, RNA
polymerases,
topoisomerases, helicase,
shuttle proteins, SnRNP
proteins, SnoRNP proteins,
histones, etc.
Ribosomal Subunits,
mRNA, tRNA, certain
shuttle proteins
Excreted proteins, proteins
destined to membranes in
secretory pathway, acid
hydrolases, signal
peptidase, etc.
Discussion 10: Signaling
RER
Golgi
Cytoplasm
Golgi
Lysosome
MCB 150
11 mer (would
have to have a
signal sequence
first, then the 14
mer which gets
modified to the 11
mer)
mannose-6phosphate
RER
Carbohydrate or
oligosaccharide
Starts out on dolichol, gets
transferred via N linked
glycosylation onto an
asparagine molecule of
the incoming protein
Branched chain
of sugars
arranged in a
particular
manner
proteins that function in
the golgi, acid hydrolase,
anything that is going
through secretory
pathway
RER
Mannose-6phosphate
6th mannose of the 11 mer
See the previous
2 answers
acid hydrolases
mitochondrial
transit sequence (or
presequence)
Cytoplasm
Amino acid
sequence
Part of the transported
protein at the amino
terminus
Basic/positively
charged amino
acids
Mt ribosomal proteins, mt
DNA and RNA
polymerases, transit
peptidase (MPP),
chaperone proteins,
chaperonin proteins,
anything needed for ETC
not present in mt genome,
porins, etc.
Mitochondria
6