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Alan Lin

Publications and source records attributed to Alan Lin.

4 recordsLinked to original sources
PubMed2006

Mapping the essential structures of human ribosomal protein L7 for nuclear entry, ribosome assembly and function.

Human large subunit protein L7 carries multiple nuclear localization signals (NLS) in its structure: there are three monobasic partite NLSs at the NH2-region of the first 54 amino acid residues and a bipartite in the middle section at position of 156-167. The C-region of the last 50 amino acid residues displays membrane binding nature, and might involve in forming a nuclear microbody for pre-nucleolar ribosome assembly. The middle section covers 144 amino acid residues which are essential for the structure and function of ribosome. This is evident from findings that truncated L7 without the NH2-region or the C-region, or missing both regions, is capable of reaching nucleolus and incorporating in ribosome, however, only ribosomes bearing truncated L7 without the NH2-region is capable of engaging in polysome formation. Combining with the phylogenic findings from homologous sequence alignment, the NH2-region of L7, besides being as a eukaryotic expansion segment, can be excluded from building a functional eukaryotic ribosome.

Amino Acid Sequence↗
PubMed2006

Polyunsaturated fatty acids mobilize intracellular Ca2+ in NT2 human teratocarcinoma cells by causing release of Ca2+ from mitochondria.

In a variety of disorders, overaccumulation of lipid in nonadipose tissues, including the heart, skeletal muscle, kidney, and liver, is associated with deterioration of normal organ function, and is accompanied by excessive plasma and cellular levels of free fatty acids (FA). Increased concentrations of FA may lead to defects in mitochondrial function found in diverse diseases. One of the most important regulators of mitochondrial function is mitochondrial Ca(2+) ([Ca(2+)](m)), which fluctuates in coordination with intracellular Ca(2+) ([Ca(2+)](i)). Polyunsaturated FA (PUFA) have been shown to cause [Ca(2+)](i) mobilization albeit by unknown mechanisms. We have found that PUFA but not monounsaturated or saturated FA cause [Ca(2+)](i) mobilization in NT2 human teratocarcinoma cells. Unlike the [Ca(2+)](i) response to the muscarinic G protein-coupled receptor agonist carbachol, PUFA-mediated [Ca(2+)](i) mobilization in NT2 cells is independent of phospholipase C and inositol-1,4,5-trisphospate (IP(3)) receptor activation, as well as IP(3)-sensitive internal Ca(2+) stores. Furthermore, PUFA-mediated [Ca(2+)](i) mobilization is inhibited by the mitochondria uncoupler carboxyl cyanide m-chlorophenylhydrozone. Direct measurements of [Ca(2+)](m) with X-rhod-1 and (45)Ca(2+) indicate that PUFA induce Ca(2+) efflux from mitochondria. Further studies show that ruthenium red, an inhibitor of the mitochondrial Ca(2+) uniporter, blocks PUFA-induced Ca(2+) efflux from mitochondria, whereas inhibitors of the mitochondrial permeability transition pore cyclosporin A and bongkrekic acid have no effect. Thus PUFA-gated Ca(2+) release from mitochondria, possibly via the Ca(2+) uniporter, appears to be the underlying mechanism for PUFA-induced [Ca(2+)](i) mobilization in NT2 cells.

Calcium↗
PubMed2002

Domain swapping in ribonuclease T1 allows the acquisition of double-stranded activity.

A mutant of ribonuclease T1 (RNase T1), denoted RNase Talpha, that is designed to recognize double-stranded ribonucleic acid was created. RNase Talpha carries the structure of RNase T1 except for a part of its loop L3 domain, which has been swapped for a corresponding domain from alpha-sarcin. The RNase Talpha maintains the pleated beta-sheet structure and retains the guanyl-specific ribonuclease activity of the wild-type RNase T1. A steady-state kinetic study on the RNase Talpha-catalyzed transesterification of GpU dinucleoside phosphates reveals a slightly reduced K(m) value of 6.94 x 10(-7) M. When the stranded specificity is examined, RNase Talpha catalyzes the hydrolysis of guanine base not only of single-stranded but also, as by design, of double-stranded RNA. The change of stranded specificity suggests the feasibility of using domain swapping to make a substrate-specific ribonuclease. This study suggests that the loop L3 in RNase T1 can be used as a 'cassette player' for inserting a functional domain to make ribonuclease of various specificities.

Base Sequence↗