Sandbox Reserved 473: Difference between revisions

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Kinesin is a superfamily of motor proteins, one of three major known groups of molecular motors. The other two groups are myosin and dynein. These molecular motors convert chemical energy into mechanical energy through ATP hydrolysis for transport within the cell.

Kinesin is known for its directed “walking” motion along microtubules, which are key components of the cell cytoskeleton. Kinesin is believed to transport large cargo such as organelles, vesicles, and even chromosomes during mitosis and meiosis in all eukaryotic organisms ~~[1]~~.

Kinesin is known for its directed “walking” motion along microtubules, which are key components of the cell cytoskeleton. Kinesin is believed to transport large cargo such as organelles, vesicles, and even chromosomes during mitosis and meiosis in all eukaryotic organisms <ref>Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.</ref>.

== Structure ==

The structure of several kinesins have been elucidated primarily by X-ray crystallography, but also by electron microscopy [7]. The structure of conventional kinesin, a particular type of kinesin so named because it has been the most studied, is displayed at right. Conventional kinesin is a homodimer composed of two subunits, each with a heavy-chain (KHC) and light-chain (KLC) domain ~~[1]~~[4]. Together, these units form a protein composed of three main regions: the head, the stalk, and the tail. (NEED A FIGURE) The tail is responsible for binding the cargo. The stalk usually consists of a structure similar to a coiled coil that helps to secure the two monomers together. The head, also known as the motor domain or the heavy chain, is responsible for microtubule binding and catalytic activity. This motor domain is the most conserved element among all kinesins, with 35% sequence homology across all kinesins [4]. The stalk and tail share little homology, suggesting the diversity of cargo that different kinesins bind [4].

The structure of several kinesins have been elucidated primarily by X-ray crystallography, but also by electron microscopy [7]. The structure of conventional kinesin, a particular type of kinesin so named because it has been the most studied, is displayed at right. Conventional kinesin is a homodimer composed of two subunits, each with a heavy-chain (KHC) and light-chain (KLC) domain <ref>Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.</ref>[4]. Together, these units form a protein composed of three main regions: the head, the stalk, and the tail. (NEED A FIGURE) The tail is responsible for binding the cargo. The stalk usually consists of a structure similar to a coiled coil that helps to secure the two monomers together. The head, also known as the motor domain or the heavy chain, is responsible for microtubule binding and catalytic activity. This motor domain is the most conserved element among all kinesins, with 35% sequence homology across all kinesins [4]. The stalk and tail share little homology, suggesting the diversity of cargo that different kinesins bind [4].

Key features within the motor domain include the <scene name='Sandbox_Reserved_473/Atp_binding_site/2'>ATP/ADP binding site</scene>, the neck and neck linker, and the relay helix. The ATP-binding site consists of a P-loop motif common not only to kinesin, but also to myosin as well as several G-proteins which also have nucleotidase activity. This homology suggests a common ancestor among these proteins [4].

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=== Directionality ===

Kinesins walk along microtubules, which are a key component of the cytoskeleton and are composed of heterodimers of α- and β-tubulin. A microtubule is in the shape of a hollow cylinder with a circumference of 13 tubulin units [6]. The heterodimers layer in a helical fashion, giving the microtubule polarity. The ends are labeled as plus and minus, with the minus-end typically anchored near the center of the cell at a centrosome, and the plus-ends branching out towards the cell membrane ~~[1]~~. This polarity is critical for the directed movement of kinesin because it allows the kinesin to recognize the directionality of the microtubule and transport its cargo in the right direction. Kinesins travel in only one direction along the microtubule. Typically, they travel from the minus end to the plus end, but some kinesins (such as ncd) travel in the opposite direction [4].

Kinesins walk along microtubules, which are a key component of the cytoskeleton and are composed of heterodimers of α- and β-tubulin. A microtubule is in the shape of a hollow cylinder with a circumference of 13 tubulin units [6]. The heterodimers layer in a helical fashion, giving the microtubule polarity. The ends are labeled as plus and minus, with the minus-end typically anchored near the center of the cell at a centrosome, and the plus-ends branching out towards the cell membrane <ref>Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.</ref>. This polarity is critical for the directed movement of kinesin because it allows the kinesin to recognize the directionality of the microtubule and transport its cargo in the right direction. Kinesins travel in only one direction along the microtubule. Typically, they travel from the minus end to the plus end, but some kinesins (such as ncd) travel in the opposite direction [4].

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== References ==

[1] Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.

[2] Vale, R.D. and Milligan, R.A. (2000.) The way things move: looking under the hood of molecular motor proteins. Science 288(5463): 88-95.

Sandbox Reserved 473: Difference between revisions

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@@ Line 8: / Line 8: @@
 Kinesin is a superfamily of motor proteins, one of three major known groups of molecular motors. The other two groups are myosin and dynein. These molecular motors convert chemical energy into mechanical energy through ATP hydrolysis for transport within the cell.
-Kinesin is known for its directed “walking” motion along microtubules, which are key components of the cell cytoskeleton. Kinesin is believed to transport large cargo such as organelles, vesicles, and even chromosomes during mitosis and meiosis in all eukaryotic organisms [1].
+Kinesin is known for its directed “walking” motion along microtubules, which are key components of the cell cytoskeleton. Kinesin is believed to transport large cargo such as organelles, vesicles, and even chromosomes during mitosis and meiosis in all eukaryotic organisms <ref>Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.</ref>.
 == Structure ==
-The structure of several kinesins have been elucidated primarily by X-ray crystallography, but also by electron microscopy [7]. The structure of conventional kinesin, a particular type of kinesin so named because it has been the most studied, is displayed at right. Conventional kinesin is a homodimer composed of two subunits, each with a heavy-chain (KHC) and light-chain (KLC) domain [1][4]. Together, these units form a protein composed of three main regions: the head, the stalk, and the tail. (NEED A FIGURE) The tail is responsible for binding the cargo. The stalk usually consists of a structure similar to a coiled coil that helps to secure the two monomers together. The head, also known as the motor domain or the heavy chain, is responsible for microtubule binding and catalytic activity. This motor domain is the most conserved element among all kinesins, with 35% sequence homology across all kinesins [4]. The stalk and tail share little homology, suggesting the diversity of cargo that different kinesins bind [4].
+The structure of several kinesins have been elucidated primarily by X-ray crystallography, but also by electron microscopy [7]. The structure of conventional kinesin, a particular type of kinesin so named because it has been the most studied, is displayed at right. Conventional kinesin is a homodimer composed of two subunits, each with a heavy-chain (KHC) and light-chain (KLC) domain <ref>Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.</ref>[4]. Together, these units form a protein composed of three main regions: the head, the stalk, and the tail. (NEED A FIGURE) The tail is responsible for binding the cargo. The stalk usually consists of a structure similar to a coiled coil that helps to secure the two monomers together. The head, also known as the motor domain or the heavy chain, is responsible for microtubule binding and catalytic activity. This motor domain is the most conserved element among all kinesins, with 35% sequence homology across all kinesins [4]. The stalk and tail share little homology, suggesting the diversity of cargo that different kinesins bind [4].
 Key features within the motor domain include the <scene name='Sandbox_Reserved_473/Atp_binding_site/2'>ATP/ADP binding site</scene>, the neck and neck linker, and the relay helix. The ATP-binding site consists of a P-loop motif common not only to kinesin, but also to myosin as well as several G-proteins which also have nucleotidase activity. This homology suggests a common ancestor among these proteins [4].
@@ Line 31: / Line 31: @@
 === Directionality ===
-Kinesins walk along microtubules, which are a key component of the cytoskeleton and are composed of heterodimers of α- and β-tubulin. A microtubule is in the shape of a hollow cylinder with a circumference of 13 tubulin units [6]. The heterodimers layer in a helical fashion, giving the microtubule polarity. The ends are labeled as plus and minus, with the minus-end typically anchored near the center of the cell at a centrosome, and the plus-ends branching out towards the cell membrane [1]. This polarity is critical for the directed movement of kinesin because it allows the kinesin to recognize the directionality of the microtubule and transport its cargo in the right direction. Kinesins travel in only one direction along the microtubule. Typically, they travel from the minus end to the plus end, but some kinesins (such as ncd) travel in the opposite direction [4].
+Kinesins walk along microtubules, which are a key component of the cytoskeleton and are composed of heterodimers of α- and β-tubulin. A microtubule is in the shape of a hollow cylinder with a circumference of 13 tubulin units [6]. The heterodimers layer in a helical fashion, giving the microtubule polarity. The ends are labeled as plus and minus, with the minus-end typically anchored near the center of the cell at a centrosome, and the plus-ends branching out towards the cell membrane <ref>Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.</ref>. This polarity is critical for the directed movement of kinesin because it allows the kinesin to recognize the directionality of the microtubule and transport its cargo in the right direction. Kinesins travel in only one direction along the microtubule. Typically, they travel from the minus end to the plus end, but some kinesins (such as ncd) travel in the opposite direction [4].
@@ Line 45: / Line 45: @@
 == References ==
+{{reflist}}
 [1] Goldstein, L.S.B. and Philp, A.V. (1999.) The road less traveled: emerging principles of kinesin motor utilization. Annu. Rev. Cell Dev. Biol. 15, 141-183.
 [2] Vale, R.D. and Milligan, R.A. (2000.) The way things move: looking under the hood of molecular motor proteins. Science 288(5463): 88-95.