Identification of chicken nebulin isoforms of the 31-residue motifs and non-muscle nebulin.
Nebulin is a very large (M(r) 600-900kDa) actin-binding protein that is specific to skeletal muscle, and which is thought to act as a molecular template that regulates the length of sarcomere thin filaments. The 31-residue motif of nebulin contains a unique PEhXRVKXNQ consensus sequence. We have previously identified 11 different human nebulin isoforms of these 31-residue motifs. Here we present the identification of seven different isoforms (types II, III, IVa, IVb, V, VI, and X) of the 31-residue motifs in 15-day-old chicken embryo breast muscle. Isoform types II and III are also expressed in the brain, and type III is also detected in the heart, stomach, and liver. Chicken nebulin contains 11 copies of the 31-residue motif (R1a/b, R2, R3, R4, R5, R6, R7, R8, R9, R10, and R11), whereas human nebulin contains 13 copies. We confirmed the expression of nebulin in the heart, stomach, and brain in 15-day-old chicken embryos by immunofluorescence microscopy. The presence of nebulin in brain was further confirmed by in situ hybridization. These data suggest that there is even more diversity in nebulin isoforms than was previously known; this diversity likely contributes to the distinct actin filament architecture of different tissues.
Joo
Young-Mi
YM
Department of Biomedical Laboratory Science, Inje University, Kimhae 621-749, Republic of Korea.
Lee
Min-A
MA
Lee
Yeong-Mi
YM
Kim
Myong-Shin
MS
Kim
So-Young
SY
Jeon
Eun-Hee
EH
Choi
Jae-Kyoung
JK
Kim
Wang-Hee
WH
Lee
Ho-Chan
HC
Min
Byung-In
BI
Kang
Ho-Sung
HS
Kim
Chong-Rak
CR
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002642:Chick Embryo; D002645:Chickens; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D009928:Organ Specificity; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment / Q000379:methods; D020539:Sequence Analysis, Protein / Q000379:methods*; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D000596:Amino Acids; D009124:Muscle Proteins; D020033:Protein Isoforms; C035620:nebulin