CB 4

Question 1

ER & Atlastin

Answer 1

Atlastin, a GTPase, is a protein involved in constructing and shaping the ER
Abundance of atlastin leads to an increased ER membrane fusion and normal Golgi is absent
Atlastin deficient – ER becomes fragmented
Deficient atlastin has been linked to hereditary spastic paraplegia. Symptoms include leg stiffness and gait disturbances such as stumbling and tripping. This is due to difficulty in hip flexion and dorsiflexion of the foot.

Question 2

hereditary spastic paraplegia

Answer 2

• She has a spastic gait disturbance, mental retardation, and extrapyramidal symptoms.
• Note the dysmorphic features.

Question 3

Alzheimers Disease

Answer 3

defective ubiquitination may contribute to fibrillar pathology

Question 4

Proteasomes

Answer 4

• Abnormal prion proteins inhibit proteasomes
• Defective ubiquination of proteins is implicated in Parkinson disease
• Form of cystic fibrosis whereby proteasomes destroy a functional CFTR ABC transport protein that is slow to fold

Question 5

bortezomib

Answer 5

inhibits proteasomes
decreases the degradation of pro-apoptotic factors
effective against multiple myeloma

Question 6

Golgi apparatus

Answer 6

Functions
Proteins are sorted based on 
chemical zip codes such as 
the linear sequence of 
Amino acids or attached 
carbohydrate moieties.

Proteins are modified

Proteins are packaged into
vesicles

Question 7

Wilson’s disease

Answer 7

copper excretion
level of ceruloplasmin decreases
-Cu deposition in Descement’s membrane
of the cornea forming a Kayser-Fleischer ring

Question 8

Dysferlin

Answer 8

Mutations of the dysferlin gene
are found in three types of
muscular dystrophy:

1) Miyoshi myopathy,
2) limb-girdle muscular dystrophy type 2b, and
3) distal myopathy tibialis anterior muscle onset.

Question 9

forms of muscular dystrophy in dysferlin….

Answer 9

All three forms are characterized
by muscle weakness and atrophy
of distal (principally the leg) or
proximal limb muscles.

Question 10

proinsulinemia

Answer 10

Mutated proinsulin is missorted
into the unregulated (constitutive)
secretory pathway.

Prohormone converting enzymes
are properly sorted into the
regulated pathway.

Consequently, there is an absence
of prohormone converting enzyme
activity in the unregulated
pathway.

Question 11

possible fates of endocytosed receptors and ligans

Answer 11

• receptor is recycled and ligand is degraded
• receptor and ligand are recycled
• recptor and ligand are degraded
• receptor and ligand are transported across cell and secreted (transcytosis)

Question 12

Achondroplasia

Answer 12

due to recycling of FGFR3 back to the surface and amplifying the signal
-leading common cause of dwarfism

Question 13

Mucolipidosis

Answer 13

results from defective synthesis of M6P

Question 14

Autophagic pathways

Answer 14

• macroautophagy
• microautophagy
• chaperone mediated autophagy

Question 15

lysosomes

Answer 15

acidophillic

Question 16

Pompe Disease

Answer 16

• glycogen storage disease
• glycogenolysis disease
• deficient alpha 1,4 glucosidase
• accumulates glycogen

Question 17

Tay Sachs Disease

Answer 17

• Sphingolipidosis
• GM2 gangliosides
• deficient hexosaminidase alpha
• accumulates GM2 ganglioside

Question 18

wilson’s disease presentation

Answer 18

• liver normal mass
• greenish yellow appearance on sectioning
• cirrhosis
• copper was 979 [normal 10-35]