Cell And Molecular Biology Final: Proteins

Front 1

Topoisomerase

Back 1

Structure: hinged clamps that open and close to bind to DNA, DNA binding cavities or temporary storage

Binding: wraps around DNA and makes a cut allowing the helix to spin

Function: relaxes (or removes) supercoils from DNA by cutting the DNA

Front 2

DNA Gyrase

Back 2

Structure: See topoisomerase

Binding: DNA helix

Function: induce or relax supercoiling of the DNA (unwinds the strands)

Front 3

Importin

Back 3

Structure: alpha and beta subunit

Binding: alpha subunit binds to the NLS of the protein being imported to the nucleus, beta subunit helps dock the importin protein to the nuclear pore complex

Function: move molecules into the nucleus by binding to the nuclear localization signal

Front 4

Exportin

Back 4

Structure: two subunits

Binding: binds to molecules containing NES sequences

Function: mediate molecules' transport out through the nuclear pores

Front 5

Nuclear RAN

Back 5

Structure: small protein, almost always accompanied by GTP

Binding: inside the nucleus, binds to imporin or exportin

Function: pomotes the release of NLS fmolecules rom importin, promotes the binding of NES molecules to exportin

Front 6

Lamins

Back 6

Structure: intermediate fillament, fibrous protein

Binding: bind to nuclear lamina

Function: serve as a structural protein and form a dense meshwork of fibers that give nucleus strength

Front 7

Primase

Back 7

Structure: grooves that slide over DNA

Binding: binds to DNA and RNA

Function: 1) synthesizes RNA fragments (~10 bases) using DNA as a template, does not require a primer 2) initiate the synthesis of a new DNA strand

Front 8

DNA Polymerase I

Back 8

Structure: said to represent a hand, alpha helix fingers

Binding: only bacterial cells, binds to DNA

Function: DNA synthesis, removes and replaces RNA primers used in DNA replication, repairs damaged DNA

Front 9

DNA Polymerase II

Back 9

Structure: said to represent a hand, alpha helix fingers

Binding: eukaryotes only, binds to DNA

Function: nuclear and mitochondrial DNA synthesis, DNA repair, forms complex with primase and begins DNA synthesis for both leading and lagging strand

Front 10

DNA Polymerase III

Back 10

Structure: said to represent a hand, alpha helix fingers

Binding: bacteria only, binds to DNA

Function: DNA syntheis, 3' to 5' for proofreading, used in synthesis of both DNA strands

Front 11

DNA Ligase

Back 11

Structure: 2 distinct domains with an ATP binding site

Binding: binds to DNA in region of the replication fork

Function: makes phospoester bond to join together adjacent DNA strands, including Okazaki fragments

Front 12

DNA Helicase

Back 12

Structure:

Binding: binds to unwound DNA to create replication fork

Function: unwinds double-stranded DNA

Front 13

SSB

Back 13

Structure:

Binding: attach to newly exposed single strands of DNA

Function: stablilizes strands of unwould DNA in an extended configuration that allows other proteins to access it

Front 14

Telomerase

Back 14

Structure: two subunits with polypeptide folds

Binding: binds to telomeric repeat sequence

Function: using an integral RNA moleculs as template, synthesizes DNA for extension of telomeres (sequences at ends of chromosomal DNA), compensates for gradual shortening that occurs

Front 15

Condensins

Back 15

Structure: large protein complexes with pair of core subunits (SMC subunits)

Binding: found in cell nucleus and cytoplasm, binds to chromosomes

Function: chromosome assembly and segregation

Front 16

Cohesins

Back 16

Structure: multi-subunit complex with 4 core subunits

Binding: bind to newly replicated chromosomal DNA in S phase

Function: adhesive protein that holds sister chromatids together

Front 17

Motor Proteins

Back 17

Structure: 1) thin, string-like protein 2) foot-like structure

Binding: interact with cytoskeletal elements (microtubles and microfilaments)

Function: uses energy fom ATP to change in shae and exert gorce causing attaches structures to move, produce movement of the cell (specifically the chromosomes)

Front 18

Spliceosome

Back 18

Structure: large, molecular complexes consisting of five kinds of RNA combined with 200 proteins

Binding: binds to pre-mRNA

Function: removes introns from pre-mRNA

Front 19

Release Factor

Back 19

Structure: group of proteins that act seperately until termination of translation

Binding: binds to ribosoe's P site

Function: teminates translation by triggering the release of a completes polypeptide chain fro peptidyl tRNA, recognizes stop codon

Front 20

TFIIA-TFIIH

Back 20

Structure: multi-subunit protein

Binding: inteacts with TBP subunit (does not bind directly to DNA), in nucleus, acts with RNA polymerase II

Function: necessary for transcription of DNA, acts as a coactivator for transcriptional activators of RNA polymerase II

Front 21

SRP

Back 21

Structure: 6 different polypeptides with a 300 nucleotide moleculeof RNA, 3 different binding sites

Binding: binds to ER signal sequence at the N-terminus of a newly formining polypeptide chain

Function: directs the ribosome-mRNA-polypeptide complex to the surface of the ER membrane

Front 22

Signal Peptidase

Back 22

Structure: part of the translocon

Binding: binds to ER

Function: removes the ER signal sequence, involved in contraslational import

Front 23

Pore Protein

Back 23

Structure: multiple proteins that form a channel

Binding: sit in the ER membrane/ lumen

Function: form a channel through which the growing polypeptide can enter the ER lumen

Front 24

TIM

Back 24

Structure: complex of proteins

Binding: binds to inner mitochondrial membrane

Function: transport complex, aids in the uptake of specific polypeptdes into the mitochondrion

Front 25

TOM

Back 25

Structure: complex of proteins

Binding: binds to outer mitochondrial membrane

Function: involved in the uptake of specific polypepties into the mitochondrion

Front 26

TIC

Back 26

Structure: complex of proteins

Binding: binds to inner chloroplast membrane

Function: involved in uptake of specific polypeptides into the chloroplast

Front 27

TOC

Back 27

Structure: complex of proteins

Binding: binds to outer chloroplast membrane

Function: involved in uptake of specific polypeptides into the chloroplast

Front 28

Hsp70

Back 28

Structure:

Binding: bind to protein substrates

Function: chaperone protein that causes protein folding, made by the body under stress

Front 29

Transit Peptidase

Back 29

Structure:

Binding: found in mitochondrion or chloroplasts

Function: removes the transit sequence once insude the mitochondrion

Front 30

t-Snare

Back 30

Structure: complimentary to v-SNARE

Binding: binds to v-SNARE, found on target membrane

Function: vesical targeting

Front 31

v-Snare

Back 31

Structure: complimentary to t-SNARE

Binding: found on transport vesicles

Function: allow a vesicle to recognize and fuse with a target membrane

Front 32

Coiled Tethering Protein

Back 32

Structure: braided string of protein

Binding: anchored on one end to the golgi membrane, other end connects to the target vesicle

Function: act over long distances, provide specificity by connectin vesicles to their target membranes

Front 33

Multisubunit Tethering Subunit

Back 33

Structure: multisubunit protein, containint 4 to 8 individual plypeptides

Binding: binds to the various membranes and target molecule

Function: differs greatly between membranes, helps identify correct target molecule

Front 34

Rab GTPase

Back 34

Structure:

Binding: locks v-SNARE and t-SNARE together, binds to transport vesicle

Function: locks v-SNARE and t-SNARE together during binding of a transport vesicle to an appropriate target membrane

Front 35

NSF

Back 35

Structure: very small protein

Binding: found in cellular membrane

Function: mediate release of v and t-SNAREs of the donor and target membranes

Front 36

SNAPs

Back 36

**Classification of NSF**

Structure: very small protein

Binding: found in cellular membrane

Function: mediate release of v and t-SNAREs of the donor and target membranes

Front 37

Flippase

Back 37

Structure: larger protein that slides over membrane

Binding: found in lipid membranes

Function: catalyze the fip-flop of membrane lipids from one monolayer to the other

Front 38

Clathrun

Back 38

Structure: very large protein (cage like)

Binding: forms a cage arund the coated vesicles and coated pits

Function: responsible for endocytosis and other intrancellular transport

Front 39

Dynamin

Back 39

Structure: GTPase

Binding: binds directly to specific vesicle

Function: required for coated pit construction and the closing of a budding clathrin-coated vesicle