Same gene, different results

Sci­en­tists are learn­ing to their sur­prise that a sin­gle gene very of­ten func­tions dif­fer­ently in dif­fer­ent parts of the body.

Genes gen­er­ally work by pro­duc­ing some mol­e­cule that serves a giv­en func­tion in the body. How­ev­er, sci­en­tists have long known one gene can pro­duce slightly dif­fer­ent forms of the same mol­e­cule, by skip­ping or in­clud­ing cer­tain al­ter­na­tive bits of ge­net­ic code.

The new re­search in­di­cates this phe­nom­e­non, known as al­ter­na­tive splic­ing, is far more prev­a­lent and varies more be­tween tis­sues than pre­vi­ously be­lieved. Nearly all hu­man genes, about 94 per­cent, gen­er­ate more than one form of their prod­ucts, re­search­ers re­ports in the Nov. 2 on­line edi­tion of the re­search jour­nal Na­ture.

“A dec­ade ago, al­ter­na­tive splic­ing of a gene was con­sid­ered un­usu­al, ex­otic… it turns out that’s not true at al­l,” said Chris­to­pher Burge, sen­ior au­thor of the pa­per and a bi­olo­g­ist at the Mas­sa­chu­setts In­sti­tute of Tech­nol­o­gy.

Hu­man genes typ­ic­ally con­tain sev­er­al “ex­ons,” or DNA se­quences that code for ami­no acids, the build­ing blocks of large mol­e­cules called pro­teins. A sin­gle gene can pro­duce mul­ti­ple se­quences of ami­no acids, de­pend­ing on which ex­ons are in­clud­ed in the in­struc­tions that trav­el from the gene to a cel­l’s pro­tein-build­ing ma­chin­ery.

Two dif­fer­ent forms of the same pro­tein, known as iso­forms, can have dif­fer­ent, even op­po­site func­tions. For ex­am­ple, one pro­tein may set in mo­tion chains of ev­ents that lead cells to com­mit su­i­cide when nec­es­sary. A close rel­a­tive of the same pro­tein may in­stead pro­mote long­er cell sur­viv­al.

Source: http://www.world-science.net/othernews/081102_genes