Sarcomere matrix of striated muscle: In vivo phosphorylation of titin and nebulin in mouse diaphragm muscle

Somerville, Laura L.; Wang, Kuan

doi:10.1016/0003-9861(88)90174-9

Cited by 38 publications

(23 citation statements)

References 21 publications

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“…Therefore, a study was performed to examine the effects of 14 and 28 days of HU on titin localization (Table 1) and relative protein concentration ( Table 2). The monoclonal 9D10 antibody to titin recognizes an epitope in the I-band at the A-I junction in skeletal and cardiac muscle (Somerville and Wang 1988;Granzier and Irving 1995). The Ab-Z (µm) was measured from the middle of the fluorescent epitope to the midpoint of the Z-band (Figs.…”

Section: Resultsmentioning

confidence: 99%

Expression of Titin in Skeletal Muscle Varies with Hind-Limb Unloading

Kasper

Lin

2000

Biological Research For Nursing

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The effects of prolonged hind-limb unloading on titin antibody localization and expression of titin isozymes of single fibers from the synergistic slow-twitch soleus (SOL) and fast-twitch plantaris (PLN) of adult rats were studied after 14 and 28 days of hind-limb unloading (HU). Titin antibody localization and expression was not altered at 14 days of HU. However, there was a 4% loss in antibody to Z-band distance (Ab-Z) in the SOL and an increase of 8% in PLN Ab-Z after 28 days of HU. The titin and myosin heavy chain composition of single fibers and small bundles of fibers from control and unloaded muscles were examined using 2% to 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There was a marked loss of relative amounts of titin in both SOL and PLN following 28 days of HU. As the protein loads for these measures were identical, the authors conclude that these findings represent an actual loss of titin density rather than a decreased value due to a loss of total muscle mass. Laser scanning densitometry of the titin bands show a marked decrease in density and molecular weight in unloaded SOL. In the PLN, marked losses of titin density were accompanied by decreased electrophoretic motility. The results demonstrate that the titin isoform composition and titin antibody localization of skeletal muscle is altered during hind-limb unloading. Furthermore, as titin is responsible for positional stability of the sarcomere and the fiber during contraction, change in isoforms during HU may predispose atrophied muscle to injury during reuse and recovery.

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Section: Resultsmentioning

confidence: 99%

Expression of Titin in Skeletal Muscle Varies with Hind-Limb Unloading

Kasper

Lin

2000

Biological Research For Nursing

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“…It is known that titin can be phosphorylated in vivo [36]. Titin phosphory lation sties were found in different parts of its molecule, from the M line to the Z disc of the sarcomere [37].…”

Section: Study Of Seasonal Changes In Level Of Titin Phosphory Lationmentioning

confidence: 99%

Seasonal changes in isoform composition of giant proteins of thick and thin filaments and titin (connectin) phosphorylation level in striated muscles of bears (Ursidae, Mammalia)

Salmov

Vikhlyantsev

Уланова

et al. 2015

Biochemistry Moscow

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Seasonal changes in the isoform composition of thick and thin filament proteins (titin, myosin heavy chains (MyHCs), nebulin), as well as in the phosphorylation level of titin in striated muscles of brown bear (Ursus arctos) and hibernating Himalayan black bear (Ursus thibetanus ussuricus) were studied. We found that the changes that lead to skeletal muscle atrophy in bears during hibernation are not accompanied by a decrease in the content of nebulin and intact titin-1 (T1) isoforms. However, a decrease (2.1-3.4-fold) in the content of T2 fragments of titin was observed in bear skeletal muscles (m. gastrocnemius, m. longissimus dorsi, m. biceps) during hibernation. The content of the stiffer N2B titin isoform was observed to increase relative to the content of its more compliant N2BA isoform in the left ventricles of hibernating bears. At the same time, in spite of the absence of decrease in the total content of T1 in the myocardium of hibernating brown bear, the content of T2 fragments decreased ~1.6-fold. The level of titin phosphorylation only slightly increased in the cardiac muscle of hibernating brown bear. In the skeletal muscles of brown bear, the level of titin phosphorylation did not vary between seasons. However, changes in the composition of MyHCs aimed at increasing the content of slow (I) and decreasing the content of fast (IIa) isoforms of this protein during hibernation of brown bear were detected. Content of MyHCs I and IIa in the skeletal muscles of hibernating Himalayan black bear corresponded to that in the skeletal muscles of hibernating brown bear.

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“…It is believed that this kinase may actively participate in myofibrillogenesis and in other regulatory roles [Somerville and Wang, 1988], and autophosphorylation has been demonstrated [Mayans et al, 1998]. In order to see if the 700-kDa protein is phosphorylated, TSU cells were labeled with 32 P-orthophosphate.…”

Section: -Kda Protein Is Phosphorylatedmentioning

confidence: 99%

Multiple antibodies to titin immunoreact with AHNAK and localize to the mitotic spindle machinery

Wernyj

Ewing

Isaacs

2001

Cell Motil. Cytoskeleton

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Recently, the large filamentous striated-muscle protein titin has been observed in non-muscle cells, and, in one instance, has been proposed to have a nuclear function as a chromosomal component contributing to structure and elasticity. In this study, we sought to further characterize the presumptive nuclear isoform of titin. Immunofluorescence microscopy with multiple titin-specific monoclonal antibodies shows localization to the nucleus in interphase cells and to the spindle machinery in mitotic cells in all cell types examined; localization to condensed chromosomes is not observed. An abundant 700-kDa phosphoprotein is the predominant species immunoprecipitated with these antibodies. Sequencing of peptide fragments of the immunopurified protein reveals identity to AHNAK, a nuclear phosphoprotein, an identification that was confirmed by Western blot analysis with antibodies to AHNAK and peptide fragmentation patterns. Sequence comparison suggests similarities between the repetitive heptad phi+/-phiP+/-phi+/- motif in AHNAK and the PEVK region of titin, potentially explaining the cross-reactivity observed between AHNAK antibodies and titin antibodies. Interestingly, although some AHNAK antibodies stain interphase nuclei, no evidence of mitotic spindle localization is seen, suggesting that the identity of the protein at the latter location is more closely related to titin than AHNAK. This concept is further supported by observations that cell lines not expressing AHNAK have similar antititin antibody localization to the mitotic spindle. We conclude that (1) multiple titin antibodies, particularly those recognizing the PEVK region, cross-react with AHNAK, and (2) the mitotic spindle staining observed with antititin antibodies is most likely due to the association of titin or a titin-like molecule with this structure.

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Sarcomere matrix of striated muscle: In vivo phosphorylation of titin and nebulin in mouse diaphragm muscle

Cited by 38 publications

References 21 publications

Expression of Titin in Skeletal Muscle Varies with Hind-Limb Unloading

Expression of Titin in Skeletal Muscle Varies with Hind-Limb Unloading

Seasonal changes in isoform composition of giant proteins of thick and thin filaments and titin (connectin) phosphorylation level in striated muscles of bears (Ursidae, Mammalia)

Multiple antibodies to titin immunoreact with AHNAK and localize to the mitotic spindle machinery

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