Postsynaptic inhibition occurs when an inhibitory transmitter (eg, glycine, GABA) is released from a presynaptic nerve terminal onto the postsynaptic neuron.

TLS Online TPP Program

#Id: 7933

#Unit 2. Cellular Organization

Signal sequences

contain one or more positively charged amino acids adjacent to a continuous stretch of 6–12 hydrophobic residues (known as the hydrophobic core)

TLS Online TPP Program

#Id: 7934

#Unit 2. Cellular Organization

The two key components in protein targeting in ER:

Signal recognition particle (SRP)

SRP receptor

TLS Online TPP Program

#Id: 7935

#Unit 2. Cellular Organization

The SRP is a cytosolic ribonucleoprotein particle that transiently binds to both the ER signal sequence in a nascent protein and the large (60S) ribosomal subunit, forming a large complex.

TLS Online TPP Program

#Id: 7936

#Unit 2. Cellular Organization

The SRP is made up of six proteins bound to a 300-nucleotide RNA, which acts as a scaffold for the hexamer.

TLS Online TPP Program

#Id: 7937

#Unit 2. Cellular Organization

Once the ER signal sequence emerges from the ribosome, it is bound by a signal recognition particle (SRP)

TLS Online TPP Program

#Id: 7938

#Unit 2. Cellular Organization

The SRP and the nascent polypeptide chain–ribosome complex bind to the SRP receptor in the ER membrane. This interaction is strengthened by the binding of GTP to both the SRP and its receptor.