Biological lectures and addresses, delivered by the late Arthur Milnes Marshall

Marshall, Alex

doi:10.5962/bhl.title.33445

Cited by 6 publications

(11 citation statements)

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“…Observations made with the RXTE satellite on 1998 January 20 detected a 59-s pulsar, with a positional uncertainty of 10 arcmin, consistent with the position of RX J0054.9-7226 (Marshall & Lochner 1998). Subsequent observations with SAX reduced the positional uncertainty to a radius of 50 arcsec, confirming the identification with RX J0054.9-7226, and refining the pulse period to 58.969 s (Santangelo & Cusumano 1998).…”

Section: Wga J00549-7226mentioning

confidence: 68%

The optical counterparts to Be/X-ray binaries in the Magellanic Clouds

Stevens

Coe

Buckley

1999

Monthly Notices of the Royal Astronomical Society

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The fields of eight X‐ray sources in the Magellanic Clouds believed to be Be/X‐ray binaries have been searched for possible Be‐star counterparts. BVRc and Hα CCD imaging was employed to identify early‐type emission stars through colour indices and Hα fluxes. Spectroscopy of five sources confirms the presence of Hα emission in each case. Based on the positional coincidence of emission‐line objects with the X‐ray sources, we identify Be‐star counterparts to the ROSAT sources RX J0032.9‐7348, RX J0049.1‐7250, RX J0054.9‐7226 and RX J0101.0‐7206, and to the recently discovered ASCA source AX J0051‐722. We confirm the Be star nature of the counterpart to the HEAO1 source H0544‐66. In the field of the ROSAT source RX J0051.8‐7231 we find that there are three possible counterparts, each showing evidence for Hα emission. We find a close double in the error circle of the EXOSAT source EXO 0531.1‐6609, each component of which could be a Be star associated with the X‐ray source.

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Section: Wga J00549-7226mentioning

confidence: 68%

The optical counterparts to Be/X-ray binaries in the Magellanic Clouds

Stevens

Coe

Buckley

1999

Monthly Notices of the Royal Astronomical Society

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“…Conversely, Ras proteins with an intact CAAX motif but with cysteine palmitoylation site or polybasic domain mutations are predominantly cytosolic, yet retain the ability to transform NIH 3T3 fibroblasts with a 10 to 50% wild-type efficiency (14). These data may be an overestimate of their inherent biological activity, since transformed cell lines derived from these focus assays express higher levels of farnesylated, cytosolic Ras proteins than of wild-type proteins (23). The possibility that a small amount of farnesylated, cytosolic Ras protein associates with the plasma membrane and that this correctly localized protein is responsible for the biological activity cannot be formally excluded.…”

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confidence: 63%

“…In the transformation assay, as in the MAP kinase assay, myristoylation reduced the biological activities of plasma membrane-localized H-ras and K-ras with wild-type C termini (Table 3). DISCUSSION We and others have shown that geranylgeranyl in place of farnesyl at the Ras C terminus supports efficient plasma membrane localization of K-ras and H-ras, but only in the context of a wild-type hypervariable domain containing the second targeting signal (7,13 (Table 3) (14,15,23), but K-ras G12V is the more potent activator of MAP kinase in COS cells. Whether the different mechanisms of membrane attachment of K-ras and H-ras in some way modulate their interactions with effector proteins and can therefore account for these data is an intriguing proposition.…”

Section: Resultsmentioning

confidence: 99%

N-terminally myristoylated Ras proteins require palmitoylation or a polybasic domain for plasma membrane localization.

Cadwallader¹,

Paterson²,

Macdonald³

et al. 1994

Mol. Cell. Biol.

170

139

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Plasma membrane targeting of Ras requires CAAX motif modifications together with a second signal from an adjacent polybasic domain or nearby cysteine palmitoylation sites. N-terminal myristoylation is known to restore membrane binding to H-ras C186S (C-186 is changed to S), a mutant protein in which all CAAX processing is abolished. We show here that myristoylated H-ras C186S is a substrate for palmitoyltransferase, despite the absence of C-terminal farnesylation, and that palmitoylation is absolutely required for plasma membrane targeting of myristoylated H-ras. Similarly, the polybasic domain is required for specific plasma membrane targeting of myristoylated K-ras. In contrast, the combination of myristoylation plus farnesylation results in the mislocalization of Ras to numerous intracellular membranes. Ras that is only myristoylated does not bind with a high affinity to any membrane. The specific targeting of Ras to the plasma membrane is therefore critically dependent on signals that are contained in the hypervariable domain but can be supported by N-terminal myristoylation or C-terminal prenylation. Interestingly, oncogenic Ras G12V that is localized correctly to the plasma membrane leads to mitogen-activated protein kinase activation irrespective of the combination of targeting signals used for localization, whereas Ras G12V that is mislocalized to the cytosol or to other membranes activates mitogen-activated protein kinase only if the Ras protein is farnesylated.

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“…6.2.3. SXP 59.0 SXP 59.0 (1SCUBEDX J005456.4-722647, S-CUBED source SC403) is an BeXRB system, first identified as an Xray pulsar in outburst by RXTE in observations taken on 1998 January 20, with a measured period of 59.0 ± 0.2 s and designated XTE J0055-724(Marshall et al 1998). SXP 59.0 has a reported orbital period of 122.1 ± 0.38 days(Galache et al 2008) based on RXTE observations, and an independently derived optical derived period of 122.25 days, consistent with the RXTE period, was reported from analysis of OGLE I-band light curves byBird et al (2012).…”

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confidence: 99%

The First Year of S-CUBED: The Swift Small Magellanic Cloud Survey

Kennea

Coe

Evans

et al. 2018

ApJ

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The Swift Small Magellanic Cloud Survey, S-CUBED, is a high cadence shallow X-ray survey of the SMC. The survey consists of 142 tiled pointings covering the optical extent of the SMC, which is performed weekly by NASA's Neil Gehrels Swift Observatory, with an exposure per tile of 60 seconds. The survey is focused on discovery and monitoring of X-ray outbursts from the large known and unknown population of BeXRBs in the SMC. Given the very low background of Swift's X-ray telescope, even with a short exposure per tile, S-CUBED is typically sensitive to outbursts in the SMC at > 1 − 2% Eddington Luminosity for a typical 1.4M neutron star compact object. This sensitivity, combined with the high cadence, and the fact that the survey can be performed all year round, make it a powerful discovery tool for outbursting accreting X-ray pulsars in the SMC. In this paper describe results from the first year of observations of S-CUBED, which includes the 1SCUBEDX catalog of 265 X-ray sources, 160 of which are not identified with any previously cataloged X-ray source. We report on bulk properties of sources in the 1SCUBEDX catalog. Finally we focus on results of S-CUBED observations of several interesting sources, which includes discovery of three Type II outbursts from BeXRBs, and the detection of Type I outbursts and orbital periods in 6 BeXRB systems.

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Biological lectures and addresses, delivered by the late Arthur Milnes Marshall

Cited by 6 publications

References 0 publications

The optical counterparts to Be/X-ray binaries in the Magellanic Clouds

The optical counterparts to Be/X-ray binaries in the Magellanic Clouds

N-terminally myristoylated Ras proteins require palmitoylation or a polybasic domain for plasma membrane localization.

The First Year of S-CUBED: The Swift Small Magellanic Cloud Survey

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