| Caseins (CAS) |
References |
| Allergen Nomenclature Bos
d 8 |
(1) Allergen
Nomenclature Sub-Committee 2001 |
Isoallergens and Variants
| CAS |
alpha-S1 |
alpha-S2 |
beta |
kappa |
| Genetic variants |
A, B, C, D (1),
F (5) |
A, D (3) |
A1, A2, A3,
B, C, E
F-5P (4) |
A, B, B2 (2) |
|
(1) Mercier et
a. 1971, 1973
(2) Grosclaude
et al. 1972
(3) Grosclaude
et al. 1979
(4) Visser et
al. 1995
(5) Prinzenberg
et al. 1998 |
Molecular Mass
|
CAS |
alpha |
beta |
gamma |
kappa |
|
| SDS-PAGE |
24 kDa (2) |
32.4 kDa (1) |
26.6 kDa (1) |
|
19 kDa (1) |
|
|
(1) Docena et
al. 1996
(2) del Val
et al. 1999 |
Isoelectric
Point
| |
alpha-S1 |
alpha-S2 |
beta-CAS |
gamma-CAS |
kappa-CAS |
|
pI 4.9-5 |
pI 5.2-5.4 |
pI 5.1-5.4 |
|
pI 5.4-5.6 |
|
(1) Wal 1998 |
Amino Acid Sequence, mRNA,
and cDNA
| Bos d 8 |
alpha-S1 |
alpha-S2 |
beta |
kappa |
| SWISS-PROT: |
P02662 |
P02663 |
P02666 |
P02668 |
| GenBank: |
S72388,
M33123,
X59856,
M38641,
X00564 |
M16644 |
S67277
(A3), M55158,
X06359,
M15132,
M16645 |
X00565
(A),
M36641
(B2),
X14908 |
| PIR: |
KABOSB |
KABOS2 |
KBBOA2 |
KKBOB |
| Amino acids |
199 (1) |
207 (4) |
209 (3) |
169 (2) |
| mRNA |
1123 bp (5)
1172 bp (6)
1134 bp (7) |
1024 bp (11) |
1094 bp (8)
755 bp (9)
1126 bp (A3, 17) |
850 bp (6)
838 bp (10) |
| cDNA |
1862 bp (15) |
2510 bp (16) |
|
|
| Gene |
17508 bp (14) |
18483 bp (16) |
10338 bp (13) |
7595 bp (12) |
|
(1) Mercier et
al. 1971, 1973
(2) Grosclaude
et al. 1972
(3) Ribadeau-Dumas
et al. 1972
(4) Brignon et
al. 1977
(5) Nagao et al.
1984
(6) Stewart et
al. 1984
(7) Gorodetskii
et al. 1986
(8) Baev et al.
1987
(9) Jimenez-Flores
et al. 1987
(10) Gorodetskii
& Kaledin 1987
(11) Stewart
et al. 1987
(12) Alexander
et al. 1988
(13) Bonsing
et al. 1988
(14) Koczan et
al. 1991
(15) Chen et al.
1992
(16) Groenen
et al. 1993
(17) Simons et
al. 1993 |
recombinant Protein
| expression in |
alpha-S1 |
alpha-S2 |
beta |
gamma |
kappa |
| Escherichia coli |
|
|
(2) |
|
(1) |
| Transgenic mice |
(5) |
|
(3), (4) |
|
|
|
(1) Kang & Richardson
1988
(2) Simons et
al. 1993
(3) Hitchin et
al. 1996
(4) Jeng et al.
1997
(5) Rijnkels
et al. 1998 |
3D-Structure
Micelle aggregation:
CAS subunits associate in solution forming complexes
and ordered aggregates of micelles in lactoserum by colloidal calcium phosphate
and phosphoserine interactions: ratio alpha-S1 / beta / alpha-S2 / kappa-CAS
is 37% / 37% / 13% / 13% (2)
Polymerisation
kappa-CAS: monomer or multimer linked by disulfide bonds
(1) |
(1) SWISS-PROT
(2) Wal 1998 |
Posttranslational Modifications
| Numbers of |
alpha-S1 |
alpha-S2 |
beta |
kappa |
| Disulfide bonds |
- |
1 |
- |
1 |
| Glycosylation sites |
- |
- |
7-8 |
- |
| Phosphorylation |
8-9 |
10 |
4-5 |
2 |
Glycosylation of kappa-CAS:
O-glycosation sites: distribution of monosaccharide,
disaccharide, trisaccharide (straight), trisaccharide (branched), and tetrasaccharide
chains were 0.8, 6.3, 18.4, 18.5, and 56.0%, respectively (means of five
kappa-CAS) (2) |
(1) SWISS-PROT
(2) Saito &
Itoh 1992 |
Biological Function
alpha-CAS: Calcium phosphate transport capacity of milk
(1)
kappa: Micelle formation stabilizing, preventing CAS
precipitation in milk (1) |
(1) SWISS-PROT |
Location
alpha-CAS, kappa-CAS: production in mammary gland, extracellular
secretion (1) |
(1) SWISS-PROT |
Sequence Homology
alpha-S1 and S2 CAS from cow's milk: aa identity 22.5%
(2)
alpha-S1 CAS from sheep's and goat's milk: aa identity
87-89% (2)
alpha-S2 CAS from sheep's and goat's milk: aa identity
87-89% (2)
alpha-S1 and S2 CAS from sheep's and goat's milk: aa
identity 97-98% (2)
beta-CAS from sheep's and goat's milk: aa identity 91%
(1)
beta-CAS from cow's milk and human milk: aa identity
50% (3)
kappa-CAS from sheep's and goat's milk: aa identity 84%
(1) |
(1) BLAST at PIR
(2) Spuergin
et al. 1997
(3) Bernard
et al. 2000b |
Stability
| |
alpha-CAS |
beta-CAS |
kappa-CAS |
| Ca2+ sensitivity |
+ |
+ |
- |
|
(1) Wal 1998 |
| Caseins (CAS) |
References |
Frequency of Sensitization
IgE-binding to CAS in 65-100% of
patients (1) |
(1) see 7.1
Sensitization to Cow's Milk Allergens |
Allergenicity of Subunits
Major IgE- binding CAS subunits in 4 patients with CMA
and atopic dermatitis: in 1 patient alpha- and kappa-CAS, in 2 patients
alpha-CAS, and in 1 patient kappa-CAS (tested: alpha-, beta-, and kappa-CAS)
(1)
85% of 58 children presented IgE against each CAS, only
1 child was monosensitized (to kappa-CAS), allergenic potencies according
to statistical distribution of specific serum IgE levels: alpha S1-CAS
> beta-CAS >> alpha S2-CAS = kappa-CAS (RAST) (2)
IgE-binding to alpha-CAS in 100%,
beta + gamma-CAS in 50%, and kappa-CAS in 33% of 6 children with CMA (3) |
(1) Shimojo et
al. 1997
(2) Bernard
et al. 1998
(3) Restani et al. 1999 |
B-Cell Epitopes: alpha S1 CAS
IgE binding sites located on alpha S1 CAS:
| Peptides |
Positivity
in Patients |
inhibition of IgE binding
to alpha S1 CAS [%] |
Ref. |
| 1-54 (fragment) |
+ (a) |
|
(1) |
| 1-10 (synthetic peptide) |
67% (b) |
5% (max. 14%) |
(2) |
| 17-36 (synthetic peptide) |
89% (d) *
50% (d) ** |
|
(4) |
| 19-30 (synthetic peptide) |
100% (c) |
|
(2)* |
| 20-31 (synthetic peptide) |
58% (b) |
7% (max. 40%) |
(2) |
| 34-45 (synthetic peptide) |
50% (b) |
5% (max. 18%) |
(2) |
| 39-48 (synthetic peptide) |
44% (d) *
13% (d) ** |
|
(4) |
| 58-73 (synthetic peptide) |
42% (b) |
3% (max. 15%) |
(2) |
| 61-123 (fragment) |
+ (a) |
|
(1) |
| 69-78 (synthetic peptide) |
67% (d) *
0% (d) ** |
|
(4) |
| 69-78 (synthetic peptide) |
60% (d) *
0% (d) ** |
|
(5) |
| 86-103 (synthetic peptide) |
100% (b) |
19% (max. 42%) |
(2) |
| 93-98 (synthetic peptide) |
100% (c) |
|
(2)* |
| 93-102 (synthetic peptide) |
67% (d) *
13% (d) ** |
|
(4) |
| 109-120 (synthetic peptide) |
89% (d) *
13% (d) ** |
|
(4) |
| 123-132 (synthetic peptide) |
56% (d) *
13% (d) ** |
|
(4) |
| 124-135 (fragment) |
+ (a) |
|
(1) |
| 136-196 (CNBr fragment) |
+ (a) |
|
(1, 3) |
| 139-154 (synthetic peptide) |
56% (d) *
25% (d) ** |
|
(4) |
| 141-150 (synthetic peptide) |
92% (b) |
8% (max. 20%) |
(2)* |
| 159-174 (synthetic peptide) |
56% (d) *
18% (d) ** |
|
(4) |
| 165-199 (fragment) |
+ (a) |
|
(1) |
| 173-194 (synthetic peptide) |
100% (d) *
0% (d) ** |
|
(4) |
| 177-186 (synthetic peptide) |
80% (d) *
20% (+50% weak) (d) ** |
|
(5) |
| 181-199 (synthetic peptide) |
100% (a) |
92% and 30% (n=2) (b) |
(3) |
| 188-199 (synthetic peptide) |
42% (b) |
7% (max. 28%) |
(2) |
(a) EAST / RAST
(b) EAST / RAST-inhibition
(c) Pin-ELISA
(d) dot / immunoblot (SPOTs membrane
technique)
(1) 2 patients with CMA
(2) 12 patients with CMA, *similar
IgG binding
(3) 9 patients with CMA
(4) * 9 patients with persistent
CMA (4-18 years of age, IgE to cow's milk >60 kU(A)/L);
** 8 children <3 years of age
(IgE to cow's milk <30 kU(A)/L)
who are likely to outgrow CMA
(5) 36 children with CMA: * 25
with persistent CMA, and ** 11 became clinically tolerant |
(1) Otani et al.
1989
(2) Spuergin
et al. 1996
(3) Nakajima-Adachi
et al. 1998
(4) Chatchatee
et al. 2001a
(5) Vila
et al. 2001 |
B-Cell Epitopes: beta-CAS
IgE binding sites located on beta-CAS:
| Peptides |
Positivity
in Patients |
Ref. |
| 1-139 (fragment) |
+ (a) |
(1) |
| 1-93 (fragment) |
+ (a) |
(1) |
| 1-16 (synthetic peptide) |
+ (b) *
+ (b) ** |
(2) |
| 1-60 (fragment) |
+ (a) |
(1) |
| 26-93 (fragment) |
+ (a) |
(1) |
| 45-54 (synthetic peptide) |
+ (b) *
+ (b) ** |
(2) |
| 55-70 (synthetic peptide) |
+ (b) * |
(2) |
| 57-66 (synthetic peptide) |
+ (b) ** |
|
| 83-92 (synthetic peptide) |
87% (b) *
+ (b) ** |
(2) |
| 106-209 (fragment) |
+ (a) |
(1) |
| 107-120 (synthetic peptide) |
+ (b) *
+ (b) ** |
(2) |
| 110-144 (fragment) |
+ (a) |
(1) |
| 132-144 (fragment) |
+ (a) |
(1) |
| 135-144 (synthetic peptide) |
80% (b) *
+ (b) ** |
(2) |
| 149-164 (synthetic peptide) |
+ (b) * |
(2) |
| 151-160 (synthetic peptide) |
40% (+10% weak) (b) *
50% (+50% weak) (b) ** |
(3) |
| 157-185 (fragment) |
+ (a) |
(1) |
| 167-184 (synthetic peptide) |
+ (b) * |
(2) |
| 167-176 (synthetic peptide) |
40% (+40% weak) (b) *
80% (+20% weak) (b) ** |
(3) |
| 175-184 (synthetic peptide) |
50% (+10% weak) (b) *
60% (+40% weak) (b) ** |
(3) |
| 185-208 (synthetic peptide) |
+ (b) *
+ (b) ** (weak) |
(2) |
| 186-209 (fragment) |
+ (a) |
(1) |
| 193-202 (synthetic peptide) |
50% (+20% weak) (b) *
100% (b) ** |
(3) |
(a) EAST / RAST
(b) dot / immunoblot (SPOTs membrane
technique)
(1) 2 patients with CMA
(2) * 15 patients with persistent
CMA (4-18 years of age, IgE to cow's milk >60 kU(A)/L);
** 8 children <3 years
of age (IgE to cow's milk <30 kU(A)/L)
who are likely to outgrow CMA (pooled serum)
(3) 36 children with CMA: * 25
with persistent CMA, and ** 11 became clinically tolerant |
(1) Otani et al.
1989
(2) Chatchatee
et al. 2001b
(3) Vila
et al. 2001 |
B-Cell Epitopes: kappa-CAS
IgE binding sites located on kappa-CAS:
| Peptide |
Positivity
in patients |
Ref. |
| 9-26 (synthetic peptide) |
93% (b) * |
(1) |
| 21-44 (synthetic peptide) |
93% (b) *
+ (b) ** |
(1) |
| 47-68 (synthetic peptide) |
93% (b) * |
(1) |
| 53-64 (synthetic peptide) |
+ (b) ** |
(1) |
| 67-78 (synthetic peptide) |
+ (b) * |
(1) |
| 95-116 (synthetic peptide) |
+ (b) * |
(1) |
| 111-126 (synthetic peptide) |
+ (b) * |
(1) |
| 137-148 (synthetic peptide) |
+ (b) * |
(1) |
| 149-166 (synthetic peptide) |
+ (b) * |
(1) |
(a) dot / immunoblot (SPOTs membrane
technique)
(1) * 15 patients with persistent
CMA (4-18 years of age, IgE to cow's milk >60 kU(A)/L);
** 8 children <3 years
of age (IgE to cow's milk <30 kU(A)/L)
who are likely to outgrow CMA |
(1) Chatchatee
et al. 2001b |
Post-translational Phosphorylation
| IgE-binding |
response |
inhibition |
| alpha S2 CAS (variant A) a) native
and b) dephosphorylated form and c) alpha S2 CAS (variant D) lacking one
major phosphorylation site |
a = c
(on averarge) |
binding to a:
a > c > b |
| beta CAS (variant A1) a) native
and b) dephosphorylated form |
a > b |
binding to a:
a > b (n=6) |
| tryptic fragment (aa 1-25) from
beta CAS a) native and b) dephosphorylated form |
|
binding to a:
a > b (n=4) |
53 sera positive to native beta-CAS,
29 sera positive to alpha S2 CAS (variant A), and 28 sera positive to variant
D from 53 patients with symptoms of CMA and specific IgE (direct ELISA,
and ELISA inhibition) (1) |
(1) Bernard
et al. 2000a |
T-Cell Epitopes: alpha S1 CAS
alpha S1 CAS specific T-Cell Lines responsive to:
1-54 (CNBr fragment) (1)
31-50 (synthetic peptide) (1)
76-95 (synthetic peptide) (1)
91-110 (synthetic peptide) (1)
124-135 (CNBr fragment) (1)
136-155 (synthetic peptide) (1)
(1) 7 TCL from 2 patients with CMA |
(1) Nakajima-Adachi
et al. 1998 |
PBMC Proliferation
stimulation with CAS (1) |
(1) see Diagnostic
Features of CMA |
PBMC Stimulation / Cytokines
PBMC stimulation with CAS:
Tendency of (4) and significantly
higher (1) PBMC proliferation in cow's milk allergic children with atopic
dermatitis as compared to children with atopic dermatitis without cow's
milk allergy
16 of 28 CAS- or ovalbumin-specific TCC from cow's milk
and egg allergic children were CD8+; 75% of CD4+ TCC and 44% of CD8+ TCC
secreted IL-4; all TCC secreted INF-gamma (1)
27% of CD4+ CAS- specific TCCs from adolescent or adult
patients with cow's milk- responsive atopic dermatitis, and the majority
of house dust mite- specific TCCs, produced IL-4 on mitogen stimulation;
INF-gamma was produced by the majority of TCCs with both specificities
(3)
PBMC stimulation with kappa- CAS:
25 of 31 TCC from patients with milk- responsive atopic
dermatits responded to mixed CAS (alpha-, beta-, kappa-) and kappa- CAS
(2) |
(1) Reekers
et al. 1996
(2) Werfel et
al. 1996
(3) Werfel et
al. 1997b
(4) Schade et
al. 2000 |
T-Cell Lines (TCL) / Cytokines
PBMC responsiveness to alpha s1- CAS activation was rather
weak in cow's milk allergic patients; 26 alpha s1- CAS- specific T-cell
lines were established; higher frequency of CD8+ T cells which produced
INF-gamma and IL-4 (1) |
(1) Nakajima
al. 1996 |
T-Cell Clone (TCC) Reactivity
CMA in infants with atopic dermatitis
associated with production of TH-2 cytokines; number of reactive TCC
to CAS fractions (all TCC CD4+ and expressed alpha/beta T-cell receptor):
| TCC reactivity |
No. of TCC |
alpha s1- |
alpha s2- |
beta- |
kappa- |
whole CAS |
| 4 patients with CMA |
50 |
4 |
15 |
1 |
6 |
5 |
| 4 patients without CMA |
43 |
1 |
1 |
0 |
3 |
5 |
|
(1) Schade et
al. 2000 |
Alteration
of Allergenicity
| Treatment |
alpha-CAS |
beta-CAS |
kappa-CAS |
| heat denaturation |
NS (1) |
|
|
| acidic treatment (HCl) |
NS (1) |
|
|
| alkaline treatment (NaOH) |
NS (1) |
|
|
| sodium dodecyl sulfate |
NS (1) |
|
|
| urea denaturation |
NS (1) |
|
|
NS no significant difference in IgE-binding
(1) patients with CMA |
(1) Kohno et al.
1994
see also 10 Stability
of Cow's Milk Allergens |