a module $m$ is said to be coretractable if there exists a nonzero homomorphism of every nonzero factor of $m$ into $m$. we prove that all right (left) modules over a ring are coretractable if and only if the ring is morita equivalent to a finite product of local right and left perfect rings.

Nuclear-cytoskeletal connections are central to fundamental cellular processes, including nuclear positioning and chromosome movements in meiosis. The cytoskeleton is coupled to the nucleoskeleton through conserved KASH-SUN bridges, or LINC complexes, that span the nuclear envelope. KASH proteins localize to the outer nuclear membrane where they connect the nucleus to the cytoskeleton. New find...

A diverse family of proteins has been discovered with a small C-terminal KASH domain in common. KASH domain proteins are localized uniquely to the outer nuclear envelope, enabling their cytoplasmic extensions to tether the nucleus to actin filaments or microtubules. KASH domains are targeted to the outer nuclear envelope by SUN domains of inner nuclear envelope proteins. Several KASH protein ge...

Although a plethora of nuclear envelope (NE) transmembrane proteins (NETs) have been identified in opisthokonts, plant NETs are largely unknown. The only known NET homologues in plants are Sad1/UNC-84 (SUN) proteins, which bind Klarsicht/ANC-1/Syne-1 homology (KASH) proteins. Therefore, de novo identification of plant NETs is necessary. Based on similarities between opisthokont KASH proteins an...

UNC-84 is required to localize UNC-83 to the nuclear envelope where it functions during nuclear migration. A KASH domain in UNC-83 was identified. KASH domains are conserved in the nuclear envelope proteins Syne/nesprins, Klarsicht, MSP-300, and ANC-1. Caenorhabditis elegans UNC-83 was shown to localize to the outer nuclear membrane and UNC-84 to the inner nuclear membrane in transfected mammal...

The nuclear envelope links the cytoskeleton to structural components of the nucleus. It functions to coordinate nuclear migration and anchorage, organize chromatin, and aid meiotic chromosome pairing. Forces generated by the cytoskeleton are transferred across the nuclear envelope to the nuclear lamina through a nuclear-envelope bridge consisting of SUN (Sad1 and UNC-84) and KASH (Klarsicht, AN...

Inner nuclear membrane Sad1/UNC-84 (SUN) proteins interact with outer nuclear membrane (ONM) Klarsicht/ANC-1/Syne homology (KASH) proteins, forming linkers of nucleoskeleton to cytoskeleton conserved from yeast to human and involved in positioning of nuclei and chromosomes. Defects in SUN-KASH bridges are linked to muscular dystrophy, progeria, and cancer. SUN proteins were recently identified ...

Klarsicht/ANC-1/Syne/homology (KASH)/Sad-1/UNC-84 (SUN) protein pairs can act as connectors between cytoplasmic organelles and the nucleoskeleton. Caenorhabditis elegans ZYG-12 and SUN-1 are essential for centrosome-nucleus attachment. Although SUN-1 has a canonical SUN domain, ZYG-12 has a divergent KASH domain. Here, we establish that the ZYG-12 mini KASH domain is functional and, in combinat...

Linker of nucleoskeleton and cytoskeleton (LINC) complexes span the nuclear envelope and are composed of KASH and SUN proteins residing in the outer and inner nuclear membrane, respectively. LINC formation relies on direct binding of KASH and SUN in the perinuclear space. Thereby, molecular tethers are formed that can transmit forces for chromosome movements, nuclear migration, and anchorage. W...

Proper nuclear positioning is important to cell function in many biological processes during animal development. In certain cells, the KASH-domain-containing proteins have been shown to be associated with the nuclear envelope, and to be involved in both nuclear anchorage and migration. We investigated the mechanism and function of nuclear anchorage in skeletal muscle cells by generating mice wi...