Picante, caliente and pain

Question 1

What are the five classes of taste and their senses?

Answer 1

Sweet –> Energy rich nuetrients

Umani –> Amino acids

Salty –> To maintain electrolyte balance

Sour –> Warn against noxious/poisonous substance or disease state

Bitter –> Warn against noxious/poisonous substance

Question 2

Choose the best option of which receptor system does each class used for taste.

(Sweet / Umani / Salty / Sour / Bitter )

• Heterodimeric GPCR
• Form by T1R2 and T1R3 GPCRs
• Beta, and gamma subunits activate PIPLC-beta 2
• Ca@+ release from ER by IP3 receptor activates TRPM5 non-selective cation channel-lead to depolarization (intracellular) and synaptic signaling from taste receptor cell to target neurons

Answer 2

Sweet

Question 3

Choose the best option of which receptor system does each class used for taste.

(Sweet / Umani / Salty / Sour / Bitter )

• Most mammals are attracted to L-amino acid
• Humans: only sense monosodium glutamate and aspartate
• T1R1 + T1R3
• Beta and gamma subunits activate PIPLC-beta 2

Ca2+ release from ER by IP3 receptor activates (intercellular) TRPM5 non-selective cation channel-lead to depolarization and synaptic signaling from taste receptor cell to target neurons

Answer 3

Umani

Question 4

Choose the best option of which receptor system does each class used for taste.

(Sweet / Umani / Salty / Sour / Bitter )

• One set of slat taste cells are specific to sodium such that the salty you taste is primarily Na+
• Accomplished via the amiloride-sensitive sodium channel (epithelial sodium channel or ENaC)
• Increased Na+ causes increased driving force for Na+ entry and result in membrane depolarization
• Appears to be a non-overlapping amiloride-insensitive system for tasting other salts.

Answer 4

Salty

Question 5

Choose the best option of which receptor system does each class used for taste.

(Sweet / Umani / Salty / Sour / Bitter )

• tasting acdciity or protein conc. [H+]
• Accomplished via products of PKD2L 1 gene: the TRPP2 ion channel
• TRPP2 is a proton-activated non-selective cation channel, increased [H+] activates TRPP2 channels and results in membrane depolarization

Answer 5

Sour

Question 6

Choose the best option of which receptor system does each class used for taste.

(Sweet / Umani / Salty / Sour / Bitter )

• Beta and gamma subunits activate PIPLC-beta 2

Ca2+ release from ER by IP3 receptor activates TRPM5 non-selective cation channel-lead to depolarization (intercellular) and synaptic signaling from taste receptor cell to target neurons

Answer 6

Bitter

Question 7

Choose the best option

(Constitutive Dimerization / Ligand-Promoted Dimerization )

Dimers are detected under basal conditions and no change in their amount is observed upon ligand treatment, indicating that they represent stably performed

Example Sweet or Umani receptors

Answer 7

Constitutive Dimerization

Question 8

Choose the best option

(Constitutive Dimerization / Ligand-Promoted Dimerization )

Dimers are detected under basal conditions, but ligands can modulate the extent of dimer observed

Ligand treatment is a prerequisite to the detection of dimers

Answer 8

Ligand Promoted Dimerization

Question 9

What are obligate Heterodimers?

Answer 9

They are GPCR Dimerization that is necessary to function.

Question 10

True or False

All Class C GCPR that have been characterized to date are constitutive and obligated heterodimers.

GABA(B) receptor exist as GABA(B) R1 only

GABA(B) R1 and R2 monomers and homodimers do not traffic to the cell surface as efficiently as GABA(b) R1; R2 heterodimers

Sweet and umami receptors are obligate (only function as) GPCR heterodimers

Answer 10

True

False; GABA (B) exists as GABA R1 and R2 isoforms

True

True

Question 11

Spicy sensation elicited by _________, the active component of chili peppers

How is it measure?

Answer 11

capsaicin

Measured by Scoville rating

Question 12

What is this receptor? What is the function?

Answer 12

TRPV1: Ligand (capsaicin) activated non-selective cation channel (Na+ and ca2+)

Activation by capsaicin leads to membrane depolarization/excitation

Question 13

Studies transferring different segments between capsaicin-sensitive (rate, mouse, human) and insensitive (chicken, rabbit) _______ identified _____ segments as making up capsaicin binding site.

Now have TRPV1 structure with _____________ and a capsaicin-like molecule bound (by cryo0EM). Confirmed that earlier experiments to define capsaicin binding site were correct.

Answer 13

TRPV1

S3-S4

spider toxin DkTx

Question 14

True or False

There are 28 different mammalian TRP channel genes (27 in human)

All thermosensitive ion channels identified to date are TRP channels, but thermosensitivity cannot be predicted from phylogeny since ThermoTRP are found on three separate branches of the TRP family tree.

Answer 14

All True

Question 15

______ is the principal detector of environmental cold.

Application of ________ to the skin of the whole trunk in mice induces automatic and behavioral heat-gain response.

Answer 15

The menthol receptor TRPM8

Menthol