WEDNESDAY night's shooting in Queens, New York, of Run DMC's Jam Master Jay, who was working in his studio at the time, deprives the world of rap of one of its most respected pioneers, and a symbol of a less violent, more innocent era.

Jam Master Jay, whose real name was Jason Mizell, was widely considered a master of a genre that was still an underground phenomenon when he and his fellow bandmembers, Joseph Simmons (aka Run) and Darryl McDaniels (aka DMC) released their eponymous debut in 1984. For those stumbling across Run-DMC in those early days the experience could be as exhilirating as discovering The Beatles.

Although it's now common for rap albums to sell in the millions, the genre was in its

infancy at the time, and dismissed by radio stations and major record labels as a niche market. Run-DMC changed all that. With their pared-down, abrasive style, the band's debut spawned a legion of imitators and created a lasting sound that changed the way people made music. ''We always knew rap was for everyone,'' Mizell recalled in an interview with MTV last year. ''Anyone could rap over all kinds of music.''

The group's biggest single, and defining moment, however, turned out to be an unlikely collaboration with rock band Aerosmith. The mass appeal of their odd-couple duet, Walk This Way, propelled Run- DMC's third album to number one in America's R&B charts, the first rap album to do so. It also earned them the distinction of being the first rap band to air on MTV at a time when it was solidly white and interested almost exclusively in pop.

Walk This Way also proved that two distinct genres could share the same audience, radically changing the boundaries of music. Rock bands now commonly draw on rap, and vice versa. ''They took hip-hop to a level that I don't think nobody's ever taken it to this day,'' said Eminem. ''Nobody ever could take it further than they took it.''

Just 17 when the band formed in 1982, Mizell was a pioneer of scratch technique - a way of scratching needles across vinyl records to create sound. Although the role of the DJ would soon become eclipsed by that of the rapper, many of the band's early songs consisted of little more than Mizell's deft scratching, in tandem with a drum machine, a far cry from the melodic rap that was then popular.

''First parties I DJ-ed, there were no hip-hop records,'' Mizell once recalled. ''You created hip-hop from other records. We used to play in the park, hook the sound-system up to the street lamp, get the electricity that way.''

Middle-class kids from Queens in New York, Run- DMC came to epitomise a more innocent era as the genre they helped inspire turned ugly and violent in the 1990s, culminating in the murder of rap legends Tupac Shakur and Notorious B I G in 1996 and 1997. Throughout it all, Run DMC maintained a reputation for folksier material, free of the vulgarity and violence that coloured the music of their followers. ''The wave of hip-hop that we're in now is immersed in crass consumerism and ostentious wealth and extreme violence,'' says Bakari Kitwana, author of The Hip Hop Generation: Young Blacks and the Crisis in African-American Culture. ''The era that Run DMC came out of was a different time in rap, and people like Run-DMC really helped to put it on the national map.''

Russell Simmons, chairman of the Hip-Hop Summit Action Network, and co-founder of Def Jam Records, was among many yesterday who warned against attributing Mizell's murder to rap's internecine wars. ''This has nothing more to do with so-called east coast/west coast violence than the sniper murders in Washington did,'' he said.

''For nearly 20 years, Run-DMC has been the closest thing to gospel artists that the contemporary music community has had. They talked about God and their higher selves, the importance of staying away from drugs, and generally inspirational and uplifting subject matter. They represented everything good and positive about hip-hop.''

Nevertheless, the band

went through a difficult patch in the early 1990s amid a decline in record sales and

a run of personal problems besetting each of the members. Joseph Simmons was accused of rape (charges which were later dropped), and Darryl McDaniels went through a bout of alcoholism. Both men have since become born-again Christians. Throughout it all, the band continued to play hundreds of shows a year, and had been due to perform last night with Aerosmith and Kid Rock during half-time at a Washington Wizards' home game.

On the band's website, Mizell was commemorated by his own lyrics yesterday: Jay's like King Midas, as I was told/ everything that he touched turned to gold/ He's the greatest of the great, get it straight he's great/ Claim fame cause his name is known in every state/ His name is Jay

to see him play will make you say: 'God damn, that DJ made

my day!'.''

Jason Jam Master Jay Mizell, musician and rap pioneer; born January 21, 1965, died October 30, 2002.