An inventory of mucin genes in the chicken genome shows that the mucin domain of Muc13 is encoded by multiple exons and that ovomucin is part of a locus of related gel-forming mucins

Table 1 Mucins identified in man, mouse, chicken and puffer fish

Mucin	Type^a	Characteristic Pfam domain	Chicken	Human	Mouse	F. rubripes
MUC1	TM	SEA	? (0/10)^d	+	+	?
MUC2	G	VWD	+ (23/53)	+	+	+^b
MUC3	TM	SEA		+	+?^c
MUC4	TM	VWD	+ (0/23)	+	+
MUC5AC	G	VWD	+ (8/42)	+	+
MUC5B	G	VWD	+ (11/37)	+	+
MUC6	G	VWD	+ (19/31)	+	+
MUC7				+
MUC10					+
MUC12	TM	SEA		+	+?^c
MUC13	TM	SEA	+ (13/24)	+	+	+
MUC14					+
MUC15	TM			+
MUC16	TM	SEA	+ (0/16)	+	+
MUC17	TM	SEA		+	+?^c
MUC19	G	VWD		+	+
MUC20				+	+
Ovomucin		VWD	+ (45/45)

^a 'TM' refers to transmembrane domain and 'G' gel-forming mucin
^bAll VWD-containing mucins in Fugu rubripes were named Muc2, although the evolutionary relationship of these mucins to the human mucins MUC2/5AC/5B/6 is not clear.
^cThe mucin gene cluster in mouse for the Muc3/Muc12/Muc17 mucins is incompletely sequenced. A mouse mucin has been described as Muc3 [42], but is most likely the orthologue of the human MUC17.
^dThe numbers within parentheses indicate the number of exons supported by chicken ESTs as compared to the total number of exons. For Muc1, Muc5ac, and Muc16 the indicated total number of exons is a minimum number as the complete gene structure is not known.

ISSN: 1471-2164