The protein kinases DNA-PK, ATM, and ATR are activated at sites of damaged DNA

TLS Online TPP Program

#Id: 7930

#Unit 2. Cellular Organization

Secretory pathway

pathway of protein trafficking that flows through the ER

TLS Online TPP Program

#Id: 7931

#Unit 2. Cellular Organization

Microsomes

when cells are homogenized, the rough ER breaks up into small closed vesicles with ribosomes on the outside

TLS Online TPP Program

#Id: 7932

#Unit 2. Cellular Organization

Signal sequence

ER targeting sequence, located at the N-terminus of the protein

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.