a) Lysosomal proteins Lysosomal proteins as they enter the cis Golgi are phosphorylated on the specific mannose sugars attached to them leading to the formation of mannose-6- phosphates on the lysosomal proteins. The mannose-6-phosphate is identified by a receptor protein in the trans Golgi which binds to the lysosomal proteins. The transport vesicles bud from the trans Golgi network in order to transport the lysosomal proteins to late endosomes which later form lysosomes. b) Membrane proteins Membrane proteins are retrieved from the trans Golgi by endocytosis and then transported to the correct domain by transcytosis. The cytoplasmic sorting signals guide membrane proteins selectively to the basolateral plasma membrane. c) ER resident proteins ER resident proteins are transported from the cis end of the Golgi complex back to the rough endoplasmic reticulum with the help of a protein known as COPI. COPI is a protein complex that coats the vesicles transporting ER resident proteins. Solution a) Lysosomal proteins Lysosomal proteins as they enter the cis Golgi are phosphorylated on the specific mannose sugars attached to them leading to the formation of mannose-6- phosphates on the lysosomal proteins. The mannose-6-phosphate is identified by a receptor protein in the trans Golgi which binds to the lysosomal proteins. The transport vesicles bud from the trans Golgi network in order to transport the lysosomal proteins to late endosomes which later form lysosomes. b) Membrane proteins Membrane proteins are retrieved from the trans Golgi by endocytosis and then transported to the correct domain by transcytosis. The cytoplasmic sorting signals guide membrane proteins selectively to the basolateral plasma membrane. c) ER resident proteins ER resident proteins are transported from the cis end of the Golgi complex back to the rough endoplasmic reticulum with the help of a protein known as COPI. COPI is a protein complex that coats the vesicles transporting ER resident proteins..

1. a) Lysosomal proteins
Lysosomal proteins as they enter the cis Golgi are phosphorylated on the specific mannose
sugars attached to them leading to the formation of mannose-6- phosphates on the lysosomal
proteins. The mannose-6-phosphate is identified by a receptor protein in the trans Golgi which
binds to the lysosomal proteins. The transport vesicles bud from the trans Golgi network in order
to transport the lysosomal proteins to late endosomes which later form lysosomes.
b) Membrane proteins
Membrane proteins are retrieved from the trans Golgi by endocytosis and then transported to the
correct domain by transcytosis. The cytoplasmic sorting signals guide membrane proteins
selectively to the basolateral plasma membrane.
c) ER resident proteins
ER resident proteins are transported from the cis end of the Golgi complex back to the rough
endoplasmic reticulum with the help of a protein known as COPI. COPI is a protein complex that
coats the vesicles transporting ER resident proteins.
Solution
a) Lysosomal proteins
Lysosomal proteins as they enter the cis Golgi are phosphorylated on the specific mannose
sugars attached to them leading to the formation of mannose-6- phosphates on the lysosomal
proteins. The mannose-6-phosphate is identified by a receptor protein in the trans Golgi which
binds to the lysosomal proteins. The transport vesicles bud from the trans Golgi network in order
to transport the lysosomal proteins to late endosomes which later form lysosomes.
b) Membrane proteins
Membrane proteins are retrieved from the trans Golgi by endocytosis and then transported to the
correct domain by transcytosis. The cytoplasmic sorting signals guide membrane proteins
selectively to the basolateral plasma membrane.
c) ER resident proteins
ER resident proteins are transported from the cis end of the Golgi complex back to the rough
endoplasmic reticulum with the help of a protein known as COPI. COPI is a protein complex that
coats the vesicles transporting ER resident proteins.