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PTC Tasting Ability Among Primates

How and why do some people like certain foods and not others?

Taste receptor 2 member 38 (TAS3R38) is a protein that in humans is encoded by the TAS2R38 gene. TAS2R38 is a bitter taste receptor, with different genotypes associated with that ability to taste 6-n-propylthiouracil (PROP) and phenylthiocarbamide (PTC).  While scientists have long hypothesized that different taste receptor genotypes could influence tasting ability, TAS2R38 is one of the only taste receptors shown to have this function. 

In humans, the dominant form of the TAS3R38 gene, “T,” codes for the ability to taste bitter substances like PTC.  The human taster “T” phenotype is associated with the sequence “PAV” – or more specifically P49, A262 and V296. In other words, human tasters have a P (Proline) at position 49, an A (Alanine) at position 262, and a V (Valine) at position 296.  Non-tasters (with the genotype “tt” )are associated with “AVI” at these same positions.  

The Basic Local Alignment Search Tool (BLAST) is a bioinformatics tool that scientists use to study and compare DNA and protein sequences.  In this activity, students use BLAST to compare the TAS3R38 protein sequences from humans and non-human primates to answer the following research question:

Are primate species other than humans “tasters” or “non-tasters”? 

Download Predicting PTC Tasting Ability among Primates Instructions (pdf, Class Set)

Download Predicting PTC Tasting Ability among Primates Worksheet (pdf, Print a Copy for Each Student)

Download All TARSR38 Protein Sequences (docx)

Download Codons and Amino Acid Chemistries (pdf)

Download Primate Cards (pdf)

 
Making a multiple alignment and phylogenetic tree   **NEW**

1.  Click primates_bear.txt  The file will open in a new window.
2.  Copy everything.
3.  Go to the NCBI BLAST home page.
4.  Scroll to the bottom of the page and click Multiple Alignment.
5.  Paste all the sequences in the Query field and click Align.  A multiple alignment will be generated by COBALT.
6.  Scroll down to see the alignment.  Changing the conservation setting to identity will make it easier to see where the sequences differ.

If you scan the sequences, you can find the amino acids that indicate taster or non-taster by  comparing the first two rows (human taster vs. human non-taster).  Tasters have a Proline at position 49, an Alanine at 262, and a Valine at 296.   

7.  To make a phylogenetic tree, click Phylogenetic Tree.

8.  Find the polar bear sequence near the top of the tree.  Hold the cursor over the dot near the sequence.  You should see a menu appear.  Select Reroot Tree to set the polar bear sequence as the outgroup.  Outgroups are sequences that are more distantly related.  Scientists use outgroups as a reference point when they make phylogenetic trees.

9.  Evaluate the tree.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



Note to Teachers: There are currently 20 Primate Cards available for download [associated with Non-Human Primate sequences 1-20 below].

TAS3R38 Protein Sequences from Humans and Non-Human Primates
0-Human Non-Taster
0-Human Taster
1 Agile Gibbon
2 Allen's Swamp Monkey
3 Angola Colobus
4 Azara's Night Monkey
5 Black-and-White Colobus
6 Black-Capped Squirrel Monkey
7 Bonobo
8 Bornean Orangutan
9 Brown-Mantled Tamarin
10 Celebes Crested Macaque
11 Chimpanzee
12 Common Marmoset
13 Common Squirrel Monkey
14 Drill
15 Francois' Leaf Monkey
16 Golden Snub-Nosed Monkey
17 Gorilla
18 Green Monkey
19 Grivet
20 Hamadryas Baboon
21 Japanese Macaque
22 King colobus
23 Lesser Spot-Nosed Monkey
24 Northern Plains Gray Langur
25 Olive Baboon
26 Pig-Tailed Macaque
27 Proboscis Monkey
28 Red-Tailed Monkey
29 Rhesus Macaque
30 Siamang Monkey
31 Silvered Leaf Monkey
32 Stump-Tailed Macaque
33 Sumatran Orangutan
34 White-Cheeked Gibbon
35 White-Handed Gibbon
36 White-Lipped Tamarin
37 Wolf's Mona Monkey


Image Credits for Primate Cards

  1. "Agilegibbon" by Julielangford - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Agilegibbon.jpg
  2. "Agile Gibbon area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Agile_Gibbon_area.png
  3. "Allens swamp monkey" by Grendelkhan - Own work. Also available from my Flickr.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Allens_swamp_monkey.jpg
  4. "Allen's Swamp Monkey area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Allen%27s_Swamp_Monkey_area.png
  5. "Angola Colobus area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data https://commons.wikimedia.org/wiki/File:Angola_Colobus_area.png
  6. "Colobus angolensis" by Ryan E. Poplin - Angola Colobus Monkey #6. https://commons.wikimedia.org/wiki/File:Colobus_angolensis.jpg
  7. "Aotus azarae infulatus" by Rich Hoyer - Flickr. Licensed under CC BY 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Aotus_azarae_infulatus.jpg
  8. "Azara's Night Monkey area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Azara%27s_Night_Monkey_area.png
  9. "2011 Colobus guereza cropped2" by 2011_Colobus_polykomos.JPG: J. Patrick Fischerderivative work: Hic et nunc (talk) - This file was derived from: 2011 Colobus polykomos.JPG:. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:2011_Colobus_guereza_cropped2.jpg
  10. "Mantled Guereza area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Mantled_Guereza_area.png
  11. "Black-capped Squirrel Monkeys in tree". Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Black-capped_Squirrel_Monkeys_in_tree.JPG
  12. "Saimiri boliviensis distribution" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Saimiri_boliviensis_distribution.svg
  13. "Pan paniscus (female)" by © Hans Hillewaert /. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Pan_paniscus_(female).jpg
  14. "Bonobo distribution" by Africa_map_blank.svg: Eric Gaba (Sting - fr:Sting)derivative work: Alphathon /'æl.f'æ.ðɒn/ (talk) - Africa_map_blank.svg. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Bonobo_distribution.svg
  15. "Orang Utan, Semenggok Forest Reserve, Sarawak, Borneo, Malaysia" by Eleifert - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Orang_Utan,_Semenggok_Forest_Reserve,_Sarawak,_Borneo,_Malaysia.JPG
  16. "Mapa distribuicao pongo pygmaeus" by Udo Schröter - Own work. Licensed under Public Domain via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Mapa_distribuicao_pongo_pygmaeus.png
  17. "Brown-mantled Tamarin" by D. Gordon E. Robertson - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Brown-mantled_Tamarin.jpg
  18. "Saguinus fuscicollis distribution" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Saguinus_fuscicollis_distribution.svg
  19. Self-portrait of a female Celebes crested macaque (Macaca nigra) in North Sulawesi, Indonesia, who had picked up photographer David Slater's camera and photographed herself with it.
  20. "Celebes Crested Macaque area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Celebes_Crested_Macaque_area.png
  21. "Schimpanse Zoo Leipzig" by Thomas Lersch - Own work. Licensed under CC BY 2.5 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Schimpanse_Zoo_Leipzig.jpg
  22. "Pan troglodytes area" by User:Luis Fernández García - Information from Keele & al. (2006). Chimpanzee Reservoirs of Pandemic and Nonpandemic HIV-1. Scienceexpress. 25 May 2006. Map base from Image:World_map_blank_black_lines_4500px.gif.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Pan_troglodytes_area.png
  23. "Weißbüschelaffe (Callithrix jacchus)" by © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons). Licensed under CC BY-SA 4.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Wei%C3%9Fb%C3%BCschelaffe_(Callithrix_jacchus).jpg
  24. "Callithrix jacchus distribution" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Callithrix_jacchus_distribution.svg
  25. "Mono ardilla - Saimiri sciureus" by ggallice (Geoff Gallice) - http://www.flickr.com/photos/dejeuxx/5402796579/. Licensed under CC BY 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Mono_ardilla_-_Saimiri_sciureus.jpg
  26. "Saimiri sciureus distribution" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Saimiri_sciureus_distribution.svg
  27. "Drill Lincolnparkzoo" by Grendelkhan - Own work. Also available from my Flickr.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Drill_Lincolnparkzoo.jpg
  28. "Drill range map" by Bamse - self-made based on CITES data and using a blank map of Africa from commons. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Drill_range_map.svg
  29. "Trachypithecus francoisi los angeles zoo" by Junkyardsparkle - Own work. Licensed under CC0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Trachypithecus_francoisi_los_angeles_zoo.jpg
  30. "Trachypithecus francoisi distribution" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Trachypithecus_francoisi_distribution.svg
  31. "Golden Snub-nosed Monkeys, Qinling Mountains - China" by Giovanni Mari - Flickr. Licensed under CC BY-SA 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Golden_Snub-nosed_Monkeys,_Qinling_Mountains_-_China.jpg
  32. "Golden Snub-nosed Monkey area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Golden_Snub-nosed_Monkey_area.png
  33. "Gorilla gorilla at the Bronx Zoo 007" by Postdlf from w. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Gorilla_gorilla_at_the_Bronx_Zoo_007.jpg
  34. "Western Gorilla area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Western_Gorilla_area.png
  35. "Bijilo-Portrait-of-a-Callithrix-Monkey" by Bjørn Christian Tørrissen - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Bijilo-Portrait-of-a-Callithrix-Monkey.jpg
  36. "Chlorocebus sabaeus distribution" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Chlorocebus_sabaeus_distribution.svg
  37. "AwasaVervet" by Joe Castleman (Gyrofrog) - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:AwasaVervet.jpg
  38. "Grivet area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Grivet_area.png
  39. "Hamadryas baboon" by المُصوّر: مُعتز توفيق إغباريّة - Own work. Licensed under CC BY-SA 4.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Hamadryas_baboon.jpg
  40. "Hamadryas Baboon area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Hamadryas_Baboon_area.png
  41. "Snow Monkeys, Nagano, Japan" by Yblieb - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Snow_Monkeys,_Nagano,_Japan.JPG
  42. "Japanese Macaque area" by Termininja - Japanese macaques (Macaca fuscata). Licensed under GFDL via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Japanese_Macaque_area.svg
  43. "Colobus polykomos" by frank wouters - Flickr. Licensed under CC BY 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Colobus_polykomos.jpg
  44. "King Colobus area" by IUCN Red List of Threatened Species, species assessors and the authors of the spatial data.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:King_Colobus_area.png

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