MSR

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MSR1

Macrophage scavenger receptor 1, also known as MSR1, is a protein which in humans is encoded by the MSR1 gene.

MSR1 has also recently been designated CD204 (cluster of differentiation 204).

Function

This gene encodes the class A macrophage scavenger receptors, which include three different types (1, 2, 3) generated by alternative splicing of this gene. These receptors or isoforms are trimeric integral membrane glycoproteins and have been implicated in many macrophage-associated physiological and pathological processes including atherosclerosis, Alzheimer's disease, and host defense. They were thought to be expressed macrophage-specific, but recently shown to be present on different dendritic cells classes, too.

The isoforms type 1 and type 2 are functional receptors and are able to mediate the endocytosis of modified low density lipoproteins (LDLs). The isoform type 3 does not internalize modified LDL (acetyl-LDL) despite having the domain shown to mediate this function in the types 1 and 2 isoforms. It has an altered intracellular processing and is trapped within the endoplasmic reticulum, making it unable to perform endocytosis. The isoform type 3 can inhibit the function of isoforms type 1 and type 2 when co-expressed, indicating a dominant negative effect and suggesting a mechanism for regulation of scavenger receptor activity in macrophages.

EgyptAir Flight 990

EgyptAir Flight 990 (MS990/MSR990) was a regularly scheduled flight from Los Angeles International Airport, United States, to Cairo International Airport, Egypt, with a stop at John F. Kennedy International Airport, New York City. On 31 October 1999, the Boeing 767 operating the route crashed into the Atlantic Ocean about 60 miles (100 km) south of Nantucket Island, Massachusetts, killing all 217 people on board. The official "probable cause" of the crash was deliberate action by the relief first officer.

As the crash occurred in international waters, the responsibility for investigating the accident fell to the Egyptian Civil Aviation Authority (ECAA) per International Civil Aviation Organization Annex 13. As the ECAA lacked the resources of the much larger American National Transportation Safety Board (NTSB), the Egyptian government asked the NTSB to handle the investigation. Two weeks after the crash, the NTSB proposed handing the investigation over to the Federal Bureau of Investigation, as the evidence suggested that a criminal act had taken place and that the crash was intentional rather than accidental. This proposal was unacceptable to the Egyptian authorities, and hence the NTSB continued to lead the investigation. As the evidence of a deliberate crash mounted, the Egyptian government reversed its earlier decision and the ECAA launched its own investigation. The two investigations came to very different conclusions: the NTSB found the crash was caused by deliberate action of the relief first officer Gameel Al-Batouti; the ECAA found the crash was caused by mechanical failure of the aircraft's elevator control system.