In skeletal and cardiac muscle, actin and myosin filaments are organized into sarcomeres that function as the fundamental unit of contraction. Skeletal muscle cells are elongated, multinucleated cells that range in length from millimeters to tens of centimeters and span the entire length of a muscle.

A dense body is analogous to the Z-discs of skeletal and cardiac muscle fibers and is fastened to the sarcolemma. Calcium ions are supplied by the SR in the fibers and by sequestration from the extracellular fluid through membrane indentations called calveoli.

The cell surface membrane is a heterogeneous mixture of proteins, cholesterol, and lipids including glycero-, phospho- and sphingolipids. A subset of lipid rafts present in cardiac muscle are caveolae which are morphologically distinct structures that will be the focus of this review.

The cardiac contractile cell relies on the autorhythmic cell to generate an action potential and pass the impulse down the line before the cell can contract. Like the autorhythmic cell, it has protein transport channels, but they are slightly different.

Clathrin performs critical roles in shaping rounded vesicles in the cytoplasm for intracellular trafficking. Clathrin-coated vesicles (CCV) selectively sort cargo at the cell membrane, trans-Golgi network, and endosomal compartments for multiple membrane traffic pathways.

Clathrin is involved in coating membranes that are endocytosed from the plasma membrane and those that move between the trans-Golgi network (TGN) and endosomes [11]. When coating membranes, clathrin does not link to the membrane directly, but does so via adaptor proteins.

Clathrin coated vesicles (CCVs) mediate the vesicular transport of cargo such as proteins between organelles in the post-Golgi network connecting the trans-Golgi network, endosomes, lysosomes and the cell membrane.

Clathrin-coated vesicles are initiated by the accumulation of adaptor and accessory proteins that bind receptors on the plasma membrane to subsequently drive the nucleation of clathrin [41]. One role of these adaptors is to induce membrane curvature, thereby leading to membrane invagination and vesicle formation.

Clathrin constitutes the coat of vesicles involved in three receptor-mediated intracellular transport pathways; the export of aggregated material from the trans-Golgi network for regulated secretion, the transfer of lysosomal hydrolases from the trans-Golgi network to lysosomes and receptor-mediated endocytosis at the …

Receptor-mediated endocytosis (RME), also called clathrin-mediated endocytosis, is a process by which cells absorb metabolites, hormones, proteins – and in some cases viruses – by the inward budding of the plasma membrane (invagination).

Clathrin-coated pits are normally restricted to the region of the plasma membrane by the cortical cytoplasm actin organization. Relaxation of this actin assembly by proteins such as latrunculin B allows movement of the coated pits.

138. Which of the following is a difference between the coats of COPII- and clathrin-coated vesicles? The inner layer of adaptor proteins of COPII-coated vesicles overlap extensively, while those of clathrin-coated vesicles do not overlap.

Clathrin coated pits are specialized patches at the plasma membrane that concentrate receptors, curve to form an invagination and bud off with their receptor cargo in the process of clathrin mediated endocytosis (CME) (Robinson, 2015).

The vesicle “coat” is a collection of proteins that serve to shape the curvature of a donor membrane, forming the rounded vesicle shape. Coat proteins can also function to bind to various transmembrane receptor proteins, called cargo receptors.

They are vacuoles, vesicles that contain mostly water; lysosomes, cellular vesicles that contain digestive enzymes; transport vesicles that move molecules within the cell; and secretory vesicles that contain materials that are to be secreted into the cell.

1 : containing, composed of, or characterized by vesicles vesicular lava. 2 : having the form or structure of a vesicle. 3 : of or relating to vesicles.

A portion of the plasma membrane is invaginated, coated with molecules of the protein clathrin, and pinched off forming a membrane-bounded vesicle called an endosome. There are three types of endocytosis. Phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Terms in this set (9)

• types of vesicular transport. endocytosis and exocytosis.
• endocytosis. refers to all vesicular processes that bring matter in the cell.
• exocytosis. all vesicular processes that release material from the cell.
• exocytosis process.
• main events of endocytosis.
• types of endocytosis.
• phagocytosis.
• pinocytosis.

There are two types of vesicle transport, endocytosis and exocytosis (illustrated in Figure below). Both processes are active transport processes, requiring energy.

Vesicle transport requires energy, so it is also a form of active transport. There are two types of vesicle transport: endocytosis and exocytosis.

Vesicular transport is thus a major cellular activity, responsible for molecular traffic between a variety of specific membrane-enclosed compartments. For example, lysosomal enzymes must be transported specifically from the Golgi apparatus to lysosomes—not to the plasma membrane or to the ER.

Osmosis is a passive transport process during which water moves from areas where solutes are less concentrated to areas where they are more concentrated.

The four major types of passive transport are (1) simple diffusion, (2) facilitated diffusion, (3) filtration, and (4) osmosis.

Passive transport is a type of membrane transport that does not require energy to move substances across cell membranes. The four main kinds of passive transport are simple diffusion, facilitated diffusion, filtration, and/or osmosis.

When a molecule moves down its concentration gradient is it participating in passive transport; moving up the concentration gradient requires energy making it active transport.

Even when equilibrium is reached, particles do not stop moving across the cell membrane. Although it may seem as if the concentrations are not changing, nearly equal numbers of particles cross the membrane in both directions. This means that there is no net change in the concentration of the substances.

Passive transport is along the gradient and requires no energy, like gas spreading out from a corner of a room. Active transport is against the gradient and requires energy, in this case, in the form of ATP.