Repression-Trp aporepressor dimer binds high tryptophan, changes conformation with high affinity for trp operator Tryptophan is a corepressor

 

TLS Online TPP Program

#Id: 8226

#Unit 2. Cellular Organization

I-cell disease

• almost all of the hydrolytic enzymes are missing from the lysosomes of many cell types.

• mis-sorting has been traced to a defective or missing GlcNAc phosphotransferase.

TLS Online TPP Program

#Id: 8311

#Unit 2. Cellular Organization

Actin,

basic building block of microfilaments extraordinarily well conserved among eukaryotes.

TLS Online TPP Program

#Id: 8312

#Unit 2. Cellular Organization

Actin exists as: 

a globular monomer -G-actin 

a filamentous polymer- F-actin

TLS Online TPP Program

#Id: 8313

#Unit 2. Cellular Organization

3 isoforms of actin-

α - expressed only in muscle cells

β and γ - found together in almost all non-muscle cells

TLS Online TPP Program

#Id: 8314

#Unit 2. Cellular Organization

Each actin subunit (globular or G-actin) is a 375-amino-acid polypeptide contains a Mg+2 ion complexed with either ATP or ADP

TLS Online TPP Program

#Id: 8315

#Unit 2. Cellular Organization

Actin can reversibly assemble into filaments that consist of two helices of actin subunits