Color Coat Genetics

Question 1

What are the 2 basic pigments?

Answer 1

Eumelanin and pheomelanin

Question 2

What is the main protein that eumelanin and pheomelanin derived from?

Answer 2

Tyrosine in melanocytes

Question 3

What steps does tyrosinase take to convert Tyrosine into the 2 main pigments?

Answer 3

Tyrosine is converted into 3,4 dihydroxyphenylalanine (dopa), then dopaquinone, then eumelanin OR pheomelanin

Question 4

At the C locus, what is C the allele for in dogs and cats?

Answer 4

Full color

Question 5

At the C locus, what is the c^ch allele?

Answer 5

chinchilla

Question 6

How does the chinchilla allele (c^ch) affect coat color?

Answer 6

It reduces pheomelanin, so that tan becomes cream.

Question 7

What are the alleles at the C locus in dogs?

Answer 7

C, c^ch, c^e, c

Question 8

What does c^e code for?

Answer 8

white with dark eyes and a dark nose (aka. Samoyed)

Question 9

What does the c allele code for in both dogs and cats?

Answer 9

true albino- no pigment whatsoever

Question 10

What are the alleles at the C locus in cats?

Answer 10

C, c^b, c^s, c

Question 11

The c^b allele encodes what color trait?

Answer 11

brown (i.e. Burmese)

Question 12

What does the c^s allele encode?

Answer 12

thremolabile melanogenesis (seen in Siamese)

Question 13

The C locus is responsible for encoding what enzyme?

Answer 13

Tyrosinase

Question 14

What do the Extension Series and the Agouti series affect the function of?

Answer 14

They affect the function of the melanocyte-stimulating hormone receptor (MSHR)

Question 15

What is MSHR?

Answer 15

a 7-transmembrane domain, G-protein coupled receptor

Question 16

alpha-MSH binds to MSHR and stimulates it to make what pigment?

Answer 16

eumelanin

Question 17

What does the E locus code for?

Answer 17

a receptor, specifically MCR1 (also known as

Question 18

What are the alleles at the E locus?

Answer 18

E^m, E, e

Question 19

What are the alleles at the E locus in cats?

Answer 19

E and e

Question 20

What does E^m code for in dogs?

Answer 20

Black Mask (Pug)

Question 21

What does E code for in dogs?

Answer 21

it restricts pheomelanin production (so that the coat will be dark throughout because eumelanin takes over)

Question 22

What does e code for in dogs?

Answer 22

extension of pheomelanin in the entire coat with a dark nose, eyes, and footpads

Question 23

What does the E code for in cats?

Answer 23

E is full color

Question 24

What does the e code for in cats?

Answer 24

“amber” only seen in Norwegian Forrest Cat. It affects the hue of the yellow seen

Question 25

What locus is identified as the paracrine-signaling molecule?

Answer 25

the Agouti Locus

Question 26

How does the agouti peptide from the A locus interact with MCR1 produced by the E Locus?

Answer 26

It is a paracrine signaling molecule that inhibits the binding of melanocortins to MCR1. (It's an antagonist gene to the MCR1 made by the E locus)

Question 27

What are the alleles for the A locus in a dog?

Answer 27

a^y, a^w, a^t, a,

Question 28

What does a^y code for?

Answer 28

tan, sable, red (pheomelanin), this is the dominant allele because when it is on, it always inhibiting the MCR1.

Question 29

What does a^w code for?

Answer 29

agouti (alternating dark and light bands on hairs)

Question 30

what does a^t code for?

Answer 30

dark trunk, tan extremities (Doberman pinscher)

Question 31

What does a code for?

Answer 31

recessive black (full color)- the agouti peptide is inhibited

Question 32

What are the a alleles at the A locus in the cat?

Answer 32

A and a

Question 33

What do the A and a alleles code for?

Answer 33

``` A= agouti a= non-agouti (full- color) ```

Question 34

The agouti peptide must be expressed to have a tabby cat. True/ False?

Answer 34

False: the agouti peptide is NOT necessary for the expression of tabby in cats

Question 35

What is the K locus?

Answer 35

the Dominant Black locus- it encodes for CBD103

Question 36

What is CBD103?

Answer 36

A beta-defensing

Question 37

How does action does CBD103 have?

Answer 37

it interacts with agouti peptide and prevents it from binding to MCR1

Question 38

What are the alleles at the K locus? (**this is only in a dog)

Answer 38

K^B, k^br, k^y

Question 39

Which allele codes for brindle?

Answer 39

k^br

Question 40

Which allele codes for solid black, brown, or blue?

Answer 40

K^B- this is eumelanin pigmentation only

Question 41

What does the k^y allele code for?

Answer 41

expression of agouti alleles that will express pheomelanin-- this allele allows for the expression of yellow

Question 42

What is the mechanism behind the brindle phenotype?

Answer 42

it is epigenetically controlled

Question 43

What is the B locus and what does it code for?

Answer 43

the Black/Brown series and it codes for a Tyrosine related protein (TRP1)

Question 44

Name the three mutations the B locus has in it.

Answer 44

1) a stop codon at exon 5 (nonsense mutaton) 2) a deleted proline at exon 5 (deletion) 3) Ser to Cys at amino acid 41 (missense mutation)

Question 45

What are the 2 alleles at the B locus in a dog and what do they code for?

Answer 45

1) B for black | 2) b for chocolate (and chocolate nose, footpads, iris)

Question 46

What are the 3 alleles at the B locus in a cat?

Answer 46

B, b, and b^e

Question 47

What does the B allele code for in cats?

Answer 47

black

Question 48

What does the b^e allele code for in cats?

Answer 48

red (seen in Abbyssianian)

Question 49

What does the b allele code for in cats?

Answer 49

chocolate (Havana Brown)