Question

The nuclear pore complex (NPC) contains_____ structures that form a gel-like matrix that allow small molecules to diffuse through, but require larger proteins to enter via importin or other nuclear chaperones.

	a.	nuclear localization signals (NLS)
	b.	nuclear lamina
	c.	structural nucleoporin
	d.	FG-nucleoporin

Answer 1

The nucleoporins are a proteirs family, constituent building blods of the nuclear pore omplex (NPO) The nudear pore mplex is a massive structure that extends aơoss the nuclear envelope, forming a gateway that regulates the flow of aơo molecules between the cell nucleus and the cytoplasm Nudear pores in tu allow the transport of water-soluble molecules aơoss the nuclear envelope. All nucleoporins s hare some basic strudural amponets. Nudeaporins aggregate to form a nudear pore complex, an otagonal ring that traverses the nucler envelope. There are three distind types of nucleoporins that each has a unique structure and function. These three types are tructural nucleoporins, membrane nucleoporins, and FG-nudenporins. FG-nudeoporins ontain repeats of the amino add res idues phenylalanine and glycine. FG-repeats are small hydrophobicsegments that break up long s tretches of hydrophilic amino adds. These FG-repeat segments are found in lorg random-coil portiors of the protein which stretch into the channel of nuclear pores and are primarily respors ible for the selective exclusivity of nudear pore omplexes These segments of FG-nuclenporirs form a mass of chains which allow sra ller molecules to diffuse through but exclude large rydro philic macromolecules. These large molecules are only able to ơoss a nuclear pore if they are acompanied by a signaling molecule that temporarily interacts with a nucleoporin's FG-repeat segment . FG-nudeoporins abo Contain a globular portion that serves an anchor for attachment to the nuclear pore omplex.