Final Exam (Lecture 22 - 26)

Question 1

Which of the following statements is incorrect?

A. Glucuronidation makes molecules more lipid soluble
B. The same molecule can have multiple sites of glucuronidation by UGT
C. UGT is superfamily, family is arabic numeral, subfamily is capital letter
D. UGT’s are only present in mammals
E. A & D

Answer 1

(A) Glucuronidation makes molecules more WATER soluble

*C - Ex. UGT1A

UGT = superfamily
1 = family
A = subfamily

Question 2

True or False UGT’s are members of a larger uridine diphosphoglycosyltransferase superfamily?

Answer 2

True - this superfamily exists in plants, animals, and bacteria

Question 3

Which of the following statements about UGT is incorrect?

A. half of protein is coded by a unique first exon
B. second part of protein is identical but coded by a set of 4 exons downstream from exon 1
C. UGT is a membrane bound protein
D. Conserved C-terminal domain of UGT defines substrate specificity
E. Liver and GI tract are major sites of UGT expression

Answer 3

(D) The VARIABLE N-TERMINAL definse substrate specificity, not the C-terminal

*E - liver and GI tract are main sites of drug metabolism

Question 4

Which of the following statements about UGT is correct?

A. Bilirubin is solely glucuronidated by UGT1A1
B. Crigler-Najjar Syndrome 1 & 2 are not associated with disorders of bilirubin glucuronidation
C. Irinotecan toxicity may be seen in UGT1A1*28 homozygotes
D. A & C
E. All of the above

Answer 4

(D) A & C are correct

*B - Crigler-Najjar Syndrome 1 & 2 ARE associated with disorders of bilirubin

Question 5

Which of the following syndromes are associated with disorders of bilirubin glucuronidation?

A. Crigler-Najjar Syndrome type 1 
B. Crigler-Najjar Syndrome type 2
C. Gilbert's syndrome
D. A & B
E. All of the above

Answer 5

(E) all of the above

Question 6

Cytosolic sulfotransferases result in which of the following?

A. increased water solubility
B. decreased passive penetration of cell membranes
C. decreased urinary and biliary excretion
D. Only A & B
E. None of the above

Answer 6

(D) only A & B are correct

*C - cytosolic sulfotransferases result in INCREASED urinary and biliary excretion

Question 7

Which of the following statements is incorrect?

A. Sulfonate group is ionized at physiologic pH
B. SULT1A1 catalyzes sulfating of small neutral phenols
C.
D.
E.

Answer 7

NEEDS MORE INFO

Question 8

True or False - almost all sulfated xenobiotics and endobiotics are biologically active?

Answer 8

False - they are biologically INACTIVE!

Question 9

How many SULT genes have been identified in humans? How many SULT families?

Answer 9

13 SULT genes

4 SULT families (SULT1, 2, 4, 6)

Question 10

Which SULT family is correctly matched to its biological role?

A. SULT1 - simple phenols like estradiol, thyroid hormones, xenobiotics, drugs
B. SULT2 - hydroxy groups of steroids
C. SULT4 - no known substrate or function
D. SULT6 - testis specific
E. All are matched correctly

Answer 10

(E) all matched correctly

Question 11

This term is defined as various forms of an enzyme that are coded by different alleles at the same locus?

Answer 11

allozymes

Question 12

This term is defined as enzymes that perform the same function, but which are coded by genes located at different loci?

Answer 12

isozymes

Question 13

What is the major xenobiotic SULT in the human liver?

Answer 13

SULT1A1 isoform

Question 14

All of the following are substrates of SULT1A1, except?

A. Minoxidil
B. APAP
C. Ethinyl estradiol
D. Metabolites of Tamoxifen
E. Amiodarone

Answer 14

(E) Amiodarone is not a SULT1A1 substrate

Question 15

Which SULT1A1 allele is responsible for thermostability differences observed in platelet SULT1A1 activity?

Answer 15

*2